(tense music) AI voice: Well done.

Now, you have a choice.

You can perform the designated ritual 25 times, or, should you choose, not at all.

When you have made your choice, click on button A or button B.

(app background music) (app beeps) You chose not to repeat your compulsion.

Well done.

I am proud of you.

(app beeps) (uplifting music) (sprinklers hissing) (uplifting music continues) (golf cart beeping, whirring) (sinister music) Don't think too much about the ball, but think about the space that you're sending it into.

Okay.

-See beyond what's in front of you.

-Thanks, Vashti.

-I'll see you next week.

-See you.

Bye.

I'm at work!

I know.

I'm here for a lesson.

Look, I got myself a club, a five iron.

If you want a golf lesson, talk to my dad.

Why are you blanking me?

What did I do?

I'm sorry.

I'm just not interested.

Right.

You can accept an expensive gift, but you won't accept my company, is that it?

-You didn't pay for it.

-What does that matter?

-Fine.

Have it back.

-No, no, no, no, no, no.

That's... that's not how it works, Vashti.

(thud) Urgh!

(dramatic music) Vashti?!

Vashti!

What's the matter?

You alright?

Vashti, what's wrong?

What... (gasps) (threatening music) (silencer pistol firing) Oh!

(pistol firing) Ah!

(gentle music) (pub chatter) Hello.

Oh, hello.

Sorry.

I'm-I'm expecting my dad.

I know.

Yeah, he told me.

Nice place.

Hi, can I get a drink please?

-Yeah, I'll be right over.

My dad told you to meet me?

We share some concerns.

Uh, about my career.

I know.

No, it's more than that, Dan.

I've spoken to some people who've dealt with Leonie's dad.

The man is dangerous.

Hi.

What can I get you?

Can I have a chai latte, please?

-Yeah, of course.

-Thanks.

-Do we have to do this here?

-Yeah, we do.

We never get a proper chance to talk at work.

I saw you go through a really tough time last year, Dan.

And I saw you pick yourself up, and you really came through for us.

I don't think I ever told you how impressed I was.

Well, you couldn't have been that impressed if you and my dad need to babysit me.

Oh, Dan... Your dad is lovely and you're really lucky.

My dad, not so lovely.

Very strict.

He stopped me from seeing my first serious boyfriend.

I got so upset, I, uh, I punched my bedroom wall.

I think I've still got the scars.

Took me about a year before I could make a fist again.

My point is that I was dating another guy within three weeks.

What?

So, you're telling me there's plenty more fish in the sea?

No.

I'm telling you, don't damage yourself when you don't need to.

(poignant music) Okay.

If we have any more questions, we'll let you know.

-Okay.

-Thanks.

-Hiya.

-Hey.

-What have we got?

-Uh, a 22-year-old woman.

She's died of a bullet wound.

Vashti Kane.

Ah.

Did anyone hear the shot?

No.

I spoke to some of the golfers, but nobody heard anything.

-Maybe used a silencer.

-Mm.

That woman I was just talking to, she was having a lesson from her, but she didn't hear anything either.

She was, uh, back at the clubhouse by the time Vashti's dad raised the alarm.

-Her dad?

-Yeah, Matthew Kane.

Club professional.

(knocking) Mr.

Kane... Do you need a few minutes?

It's okay.

Thank you.

Let's get it done.

Can you, um, tell us where you were, what you saw?

I was in the shop.

Vashti's 12 o'clock had called to cancel, so I...stepped out to let her know.

And as I approached the practice fairway, she was on the ground.

Did you see anyone?

-No.

-Can you think of anyone who might want to harm your daughter?

Well, she...mentioned some guy.

I-I don't know his name.

She'd been on a couple of dates.

She told him that was that, but... he was persistent.

And did she say why she broke it off?

She thought he was a conman.

He boasted about scamming his boss.

Did you hear anything that in retrospect may have been a gunshot?

We're trying to establish a timeline.

No.

There... there was a golf club out on the fairway.

(sinister music) A mid iron.

-Not Vashti's?

-No.

She used standard clubs.

Whoever left this was over six feet tall.

(dramatic music) (golf club swings, ball pings) (laughter) (knocking) Hi, Ma'am, quick question.

Uh, something taken down to reception?

Someone's trying to make a name for themselves.

Look at that.

Vashti Kane.

David Ellis?

David Ellis.

His wife has just reported him missing.

(scratching) (distant sirens) Maiya: Okay.

We have to treat this as top priority, especially with the threat of another death.

What do we know about David Ellis, the second victim?

Right, he was shot in the golf course, he was buried in a bunker.

Dan, forensics, anything?

Yeah, they came back on the bullets.

So both victims were killed with the same weapon, which was a Beretta 9000.

Now, uh, Mr.

Ellis's car was found in the golf club car park and forensics matched his DNA with the grip on the five iron which was found next to Vashti Kane's body.

Well, could it be the boyfriend that Vashti Kane's dad told us about?

Well, we did check his phone and her phone and there was nothing to connect them.

So, David Ellis, he's not a member of the golf club, right, he didn't have an appointment for a lesson.

So what's he doing there with a brand new club?

It's a good question.

Professor, in your opinion, are we dealing with a serial killer?

(dramatic music) No.

Categorically no.

Well, what about this cipher?

Yeah.

Have you managed to decode it?

When a cipher is this derivative, decoding it is not difficult.

Most of these symbols were used by the so-called Zodiac Killer.

Zodiac Killer.

Killed at least five people.

San Francisco, '68 to '69.

Was never caught.

Using the key from the Zodiac cipher, our 'serial killer' tells us in tedious detail, "I am collecting slaves at random to serve me in heaven.

I have two.

I will take ten more."

I thought you said he wasn't a serial killer?

I used invisible quotation marks.

This letter writer, are we saying that he is the killer?

We are.

So, how can you be sure he's not a serial killer?

Because serial killers are driven by ego.

They do not plagiarize their predecessors.

The purpose of this message is misdirection.

Okay, yeah, I get that.

However we've got nothing to lose assuming that he might be a serial killer.

(pen clicks) There will not be another murder relating to this case.

Matthew Kane: No, I've never seen him before.

The name, David Ellis?

The guy that I mentioned... The one who was being persistent.

Yeah, he had a double-barreled name.

Upper class?

She didn't say if he was.

Um, some of your daughter's things.

Thank you.

(poignant music) (sighs) (footsteps approaching) Ah, good.

You're here.

The board is keen to discuss the incident on the roof.

They have my permission.

(scoffs) To discuss it with you.

Some are willing to offer an olive branch.

Others believe that your actions have brought the university into disrepute far too often.

Kindly inform the board that I am on the cusp of accepting an offer from John Adams University in Boston.

Should we reach a mutually acceptable concordance, my shadow need never again darken their door.

Isn't that a bit of an overreaction?

With the right approach, the board may still be won over.

You and I both know I was never one for the right approach.

Hm.

(playful music) Queen takes rook.

Mm.

Rook takes queen.

Knight to queen bishop two.

Checkmate.

Mrs.

Ellis, your husband's DNA was found on this golf club.

David hated golf.

He never played in his life.

Mrs.

Ellis, we need to ask you some questions that might be a bit...painful.

Could your husband have been having an affair?

No.

100% no.

This is Vashti Kane.

Good choice of photo.

What are you saying?

Who could resist?

Do you recognize her?

I'll tell you what kind of guy David was.

Sorry, can you remind me who you are?

I'm Jack Miles.

David was my business partner.

Right.

What kind of business?

We buy... we bought job lots here and abroad.

David and Jack started the business when they were in college.

(somber music) Look, Zadie just lost her husband, and you coming in here with that, I'm sorry, but I think that's pretty low.

I'm sorry.

AI voice: Well done.

I am proud of you.

(Helena giggles) Let's try this again tomorrow.

Is it possible to select the slightly less patronizing tone?

The voice is the least of my concerns.

Oh.

You said the app was helping.

There is a side effect.

It reduces the brain's ability to make critical judgments.

That is a possible side effect, yes.

When people fall in love, the release of dopamine does much the same thing.

Hm.

Do you think it's possible that... something else might be going on?

Such as?

(chuckles) Let's keep walking.

Dan?

Chloe.

-What?

-Come here.

Jack Miles and David Ellis.

Their company's website.

Yeah?

Well, they got robbed a couple of weeks ago.

Alright.

Do we have any suspects for this?

Yeah.

Couldn't make it stick, but could be connected.

Okay.

Let's check it out.

Okay.

There are plates, you know, over there.

"There are plates, you know."

There you go, Kafka.

That's lovely.

Yes.

Home time already?

I have only just this... Sending you home before you get tired and befuddled, are they?

Don't worry, some of us are still playing with a full deck.

Wilfred informs me that Jasper's about to accept a job in Boston!

-Boston Spa?

-No, no, no.

Boston USA.

What?

Obviously our previous attempt at working together ran aground.

-America... -But this is code red.

Why has no one told me?

How will he survive?

You mean, how will you survive?

Anyway, uh, I suggest a pincer movement.

You play up the pleasures of Cambridge while I wax lyrical on the joys of sex and romance.

Why do you get the fun part?

For the simple reason I've accrued more experience than you in that particular front.

Speak for yourself.

I shall remind Jasper that he's never going to find anyone to compare with Helena in the US of A. Miss Snares?

What?

You don't have a crush on him, do you?

A crush?

What?

I have to work with him, for goodness' sake.

Okay.

What people like you can never understand, long term working relationships, -Okay.

they are more intense and more faithful than any marriage.

-Okay.

-Or marriages could ever be.

Okay.

(suspenseful music) (dog squealing) (speaker music blaring) This place is so cool.

But who buys this shit?

Set designers.

People who kit out bars.

Most of it gets shipped abroad.

We know about the burglary.

-That didn't help.

-What was stolen?

A consignment from the British Timepiece company.

Upmarket jewelry, watches.

The whole lot stolen the night it arrived.

Didn't have time to get it assessed.

And what does that mean?

It means it wasn't insured.

How much did you lose?

400,000 plus VAT.

And where were you yesterday morning?

Am I...?

I was here.

Am I a suspect?

I was here all day.

Okay, thanks for your time.

His staff already told me he was here.

You could have told me.

(upbeat music) Professor, good morning!

You appear uncharacteristically effusive.

I was just thinking, aren't we lucky to be here?

In one of the world's most beautiful cities?

Yes.

Did you know that Cambridge is a mecca for buskers?

I did not.

I must lodge a formal complaint with the council.

(phone ringing) Excuse me.

Um... I know how much you love my banana cake.

I have not yet consumed the last one.

That was months ago.

Your cakes are exceedingly... (phone ringing) durable.

Tempest?

Maiya: Have you seen the Cambridge Post?

I tend to avoid print media.

We need you here right away, Professor.

(sinister music) Of course.

Desk.

(sinister music swells) So, I've had the Chief Constable on the phone.

He wants to know if this is cipher two, what's happened to cipher one?

He also wants to know, are we investigating a serial killer, and if so, why haven't I requested the help of a specialist?

I told him we already have the services of an excellent consultant who informs me we're not, repeat not, dealing with a serial killer.

So, the Chief seems to be happy, but he made it very clear there is no room for error.

Meanwhile, Vashti Kane's phone, we'd retrieved some data from it.

There are four encounters with an individual called Alan Washington-Cave.

Alan Washington-Cave?

That's an unusual name.

Yeah.

So uncommon there's no one with that name in the UK.

It's double-barreled, though.

Vashti Kane's dad said the guy who was persistent with her had a double-barreled surname.

-Hm.

She hooked up with him at the New Vanguard Hotel in Waterbeach.

So maybe it's just an alias and this Alan Washington whatever... -It is David Ellis.

-Dan: Yes.

Maiya: Could be.

Maiya: Chloe, check the hotel CCTV.

Afternoon to you, Sir.

How may I help you?

I am looking for Mr.

Jack Miles.

Jack?

Yeah, well, the lights are on, so he'll probably be in his office.

Oh.

(trundling) Mr.

Miles.

Professor Jasper Tempest, police consultant.

-How can I help?

-Are you married?

What?

I wish to establish certain facts.

Are you married?

-No.

David Ellis, your business partner... How long had you known him?

Since primary school.

When I started school, I had no friends.

My father advised me, sit in the playground with a book and your aloofness will appear intriguing.

The other children will come to you.

(tender music) Of course they never did.

I was lucky.

David was popular.

Took me under his wing.

Can't believe what happened.

Hm.

What good is a discount if it's not the goods I ordered?

No, you listen.

I'm not shipping anything.

Organize a courier.

Come and get 'em yourself.

What's the matter?

Tell Dan thanks for the advice?

Is that supposed to be funny?

A little bit, yeah.

Sally, take a break.

Well, I didn't find it funny.

Nor did Dan.

Your little joke's gonna hold back his career.

His career?

You know I can pick up the phone and his whole life turns to shit.

-Dad!

-I'm not even gonna tell you what Wesley's lad said when I told him you was seeing an Old Bill.

No, tell me.

What did they say?

I won't go chapter and verse, but 'sleeping with the enemy' cropped up.

-It's none of their business.

-No.

It is very much their business.

Well, you can tell them that I love Dan, and if they or you can't handle that, we're done.

We're done?

I never thought I'd say that to you, Dad.

Have you any idea what it was like for me?

You in prison?

The bullying I got?

I kept it all shut away and I never for one minute stopped loving you.

But I mean it.

Don't make me choose.

(suspenseful music) Your cousins, their dad was murdered by the police.

My brother.

You know who you are, and you know where you come from.

You don't get a choice.

Course I do.

No.

No, you don't!

(door shuts) Chris, get down the office.

Come and pick me up, mate.

Chloe: Alright.

Who wants to play Spot The Difference?

Oh, great.

I'm really in the mood.

New Vanguard Hotel Bar, one month ago.

-Mm-hm.

-There's Vashti.

Enter... (mouse clicks) Alan Washington-Cave, aka David Ellis.

Oh Professor, thanks for joining.

Okay, so... (mouse clicks) Vashti and David go off together.

The room's been booked under the Washington-Cave alias.

Fast forward two hours... and look who's back.

What have they been up to?

Oh, I can't possibly imagine.

Only now, Vashti's wearing a watch.

Well, maybe she forgot to put it on earlier.

No.

Look at the way she's admiring it, she's tilting it to catch the light.

That is fling bling.

Dan: Right, well maybe this is coming together then.

(suspenseful music) So, Ellis works at the warehouse that got robbed.

He keeps one of the watches... Chloe: Yeah, 'cause he knows it's gonna get nicked anyway.

Dan: And gives it to Vashti.

Chloe: It's probably in that bag I gave back to her dad.

Dan: So, Ellis sets up the raid.

Jack Miles finds out and has him killed?

Vashti gets shot by mistake?

You see, this is where it all falls apart for me.

Why would Ellis rob his own business?

According to Companies House, David Ellis sold his shares two years ago.

But Jack Miles has an alibi.

That is imprecise.

His staff assumed he was in his office because the light was on.

But these two have been friends since they were kids.

Jack Miles, no spouse, no partner.

Looked up to David Ellis his whole life.

He suffers, I believe, from proditiophobia, a terror of betrayal.

Intimate forms of treachery cause intense distress.

They cloud judgment and can engender an overwhelming desire for revenge.

Maiya: Dan, Chloe, head to the warehouse.

I want Jack Miles in custody.

Dan: Hello?

Chloe: Light's on.

(knocking) (suspenseful music) Shit... Oh, no.

(sighs) (door creaks open) (gunshot) (glass smashing) Ah!

(dramatic music) -You okay?

-Yeah, I'm fine.

Dan... Dan!

Stop!

Stop, police!

(crates clattering) (rattling) (thud) Uh!

Ah... Seriously... Go!

Argh... (dramatic music intensifies) (ladder clattering) Urgh!

You scared of ladders?

Stuck under a bear?

We can confirm that the deceased man is Jack Miles.

He's 37 years old with no immediate family.

There is speculation that Jack Miles is the third victim of the Cipher Killer.

We have nothing more to add to the statement already issued.

In all three cases, the same weapon was used.

Yes.

Doesn't that tell you it's the same killer?

It tells us that it's the same weapon.

Why did you cover up the first cipher?

We are talking about an active serial killer here, aren't we?

I got it wrong.

Doesn't seem like the MO of a serial killer.

I told DCI Goswami that there would be no more murders connected with this case.

I put DS Winters and DC Highsmith in danger.

Oh, Jasper.

I told you that this would happen.

I have impaired my ability to think in an effort to make this relationship work.

-What?

-You pressurized me into seeing an OCD specialist.

I compromised by installing the app.

I knew the risk, but I persevered.

You did it for me?

No, you did it because your compulsions were getting worse.

Do you want to risk being unable to function?

I was never unable to function.

Jasper, a year ago you couldn't work because of intrusive images.

Look, I know it's difficult.

Our plans, and, and... becoming close to someone.

I understand, but it's not easy for me... I do not wish to discuss this.

Oh God, you made a mistake and you're blaming me?

I need some air.

Well, I need... (door slams) (dramatic music) (sighs) I thought you'd stopped all this.

I had an app.

I deleted it.

I only installed it to keep Dr.

Goldberg happy.

And now I find I have been possibly permanently cognitively impaired.

Attempting to assist the police, I fell prey to an error of judgment, and the dean, of all people, solved a chess problem before I did.

The dean?

You mean my husband?

Of all people.

It has never happened before.

And you told Dr.

Goldberg this, uh, what... Cognitive impairment.

You blamed her.

I installed the app for her.

Who else should I blame?

Jasper... We're going to have to have a chat, hm?

It's what your mother would want.

(suspenseful music) I scanned a copy of the third letter to the professor, but he hasn't responded yet.

So maybe they're meaningless.

Unlikely, because this came with the letter.

-Is that blood?

-Mm-hm.

Forensics found a match.

-Jack Miles.

-Yeah.

(desk slams) Look at the circles on the targets.

The circle closes on the right for somebody who's right-handed.

That's the case with these two letters.

But the third letter, the circle closes on the left.

This person's left-handed.

They just want us to think the serial killer's still out there.

What?

-Alright, Professor.

It's just... it's basic graphology.

I paid attention in college, alright?

(classical music) Do you take milk?

I do not take tea.

Especially when it has been brewed in a coffee pot.

Jasper, while I have none of your qualifications in psychology, I have graduated with honors many times in the school of human nature.

You realize you'll have hurt Helena's feelings.

How?

You blamed her for your failure with the police.

I merely pointed out that my cognitive impairment... Cognitive impairment, my behind!

Listen to me.

There is no argument that a large shot of ooh-la-la won't solve.

Stop fretting and seduce her.

What an excellent idea.

Perhaps I could warm up by freestyling down the Eiger.

Oh, come on... Slap on some Eau Sauvage, arrive at her doorstep with oysters and champagne, and apologize, for God's sake.

That's how you warm up.

An apology for something someone has not done is meaningless.

Jasper, Jasper, Jasper, my darling nephew.

Some of the most intensely erotic experiences I have had with a man... -Oh my God!

Oh, come on.

I'm not gonna spare you.

Those experiences came after an argument and an apology.

There are times, Aunt Zelda, when I can barely believe you are my mother's sister.

(sighs) Listen up, everyone.

Chloe's theory that the cipher letters were written by two different people has just been confirmed by the lab.

Good spot.

I'm gonna call a press conference this afternoon and put an end to this whole serial killer nonsense.

And Dan, would you let Matthew Kane know that his daughter was killed by Jack Miles, in all likelihood by accident.

-Okay.

But this isn't over.

We've still got to find Jack Miles' killer.

(knocking) Mr.

Kane?

Chlo... (suspenseful music) I'll see if I can find him.

(drawers rattling) -Argh!

-Uh!

(thud) Oh... (dramatic music) (gasping) I'm not going to prison for killing the man who murdered my daughter.

(gasps) Put the gun down.

When they find your body, you'll just be another victim of the serial killer.

There's no serial killer.

Argh!

Uh!

(thud) (struggling) Ah!

Ah... (struggling) Chloe: Uh... Leave you alone for two minutes.

(struggling) (gasping) (sighs) I saw how much the watch was worth.

After that, it was obvious.

-Was it?

-Mm.

Ellis ripped off his partner, partner found out, wanted revenge.

Vashti got in the way.

What did you do?

(suspenseful music) I broke in, through the skylight.

(alarm blaring) The office was open.

(sinister music) (door shuts) (alarm beeps off) He looked terrified.

I told him I was taking him in and wanted his gun as evidence.

Show me the gun!

He pleaded.

No, no, please, please, please, please.

You don't have to do this.

Please!

Told me hadn't meant to harm Vashti.

She wasn't meant to be there.

I'm sorry!

(gunshot) You'd heard about the cipher and you thought it would be helpful to keep the myth of the serial killer alive.

My life ended when Vashti died.

(poignant music) Home.

Prison.

What's the difference?

(gasping) (gentle music) I even outlined the potential benefits of a heartfelt apology.

Perhaps in too much detail.

Look what she gave me.

She knows what people need.

She knows what you need.

Helena is good for you.

I'll send Dr.

Goldberg some flowers.

A luxury bouquet.

And how will that help?

I'll send them from the professor's university account.

She'll think it's his way of apologizing.

Dear Helena, I am writing you this letter in the express belief that you are good for me.

I hope for nothing more than that our relationship should continue into a future wherein I can see no shadow of a further parting from you.

Right now, the professor and Dr.

Goldberg are here.

The flowers do this.

After that, it's up to them.

Hi.

Leonie: Hiya.

You okay?

I saw my dad.

Wait, what happened to your head?

Oh, it's an accident.

It's fine.

When did you see your dad?

Uh, a couple of days ago.

Oh, well, what happened?

-We talked.

-Yeah?

I was pretty angry.

Dan, he was trying to split us up.

Well, what did he say to you?

I don't know, he's... He's saying I'm letting the family down, sleeping with the enemy.

I said I didn't want to see him again.

He just gets this look.

It's so scary.

I'm sorry.

He said he picks up the phone, your life turns to shit.

Yeah.

Well, dogs that bark don't bite, so... He's also shut down my business.

(somber music) What?

Well, how did he do that?

I went over at lunchtime.

Sandy's outside, said a couple of guys showed up, changed the locks.

Told Sandy I could get back in when I dumped you.

I tried phoning him but he's blocked me.

Dan, what are we gonna do?

Oh, I don't know.

Um... Look, we'll figure something out, yeah?

(birdsong) (suspenseful music) Chloe: What have you got?

Chester Vass.

The father-in-law.

What's he done?

Somebody changed the locks to Leonie's gym.

I just want to see who.

(mouse clicks) (mouse clicks) That lands you right back in prison.

(knocking) What?

(suspenseful music) You did what?

We ordered flowers.

Yes, I know what you did.

I was just overcome by the need to give vent.

Miss Snares used the professor's account.

Oh, genius!

You are meddling in a relationship between two mature, professional people.

It is guaranteed to have the opposite effect to the one you desire.

What do we do?

Stop the delivery.

It was done in a moment of panic.

(sighs) And that cognitive impairment nonsense.

I only solved the chess problem because I'd seen it before.

The flowers are in transit.

Oh... (dog barking) The, uh, the letter you delivered was... extremely formal.

I struggle with nuance.

Among other things.

Yes.

(soft footsteps) What...what have you got on?

You look ridiculous!

What is, what is that?

-Camouflage.

Well, take it off, for goodness' sake!

What do you think you're doing?

I think I saw a delivery van just now drive off.

-Florist's van?

-I don't know.

I think so.

Oh, we're too late.

Zelda: Is that... Is that Jasper?

Miss Snares: Oh... I think the flowers must have worked.

What are they doing?

I did discern a sort of... coded message, a kind of cipher.

Sort of a lot of pressure on the pen on the word 'relationship'.

'Future'.

Uh, 'hope'.

I gave the police incorrect information and blamed you, er, for this.

I am extremely sorry.

And for any hurt that I may have caused.

And... Well, without wishing to excuse myself, the-the pressures of university (tender music) and police work are occasionally overwhelming to me, and... Jasper, would this be a good time to tell you that, uh, Linn-Beck College have written to me offering me a post teaching clinical counseling?

This would be a very good time.

When do you start?

In two weeks.

I have a sudden irresistible urge to kiss you.

(romantic music) Well, do it then.

Ooh... (gasps) They're kissing.

Zelda: Where've they gone?

Look.

(Zelda and Miss Snares laugh softly) We've done it.

High five!

(laughter) Yeah.

(engine rumbling) Oh God, not now.

(engine slows, idling) Er, are those for Dr.

Helena Goldberg, by any chance?

Yep.

I am she.

I am the lady doctor.

I'll need to see some ID.

Dr.

Goldberg, how are you?

I'm very well, thank you so much.

Proof enough, my good man?

-Uh... -Thank you, Sir.

Thank you so much.

Why are you talking like that?

I have no idea.

(engine rumbling) (gentle music) I think this is the beginning of a beautiful friendship.

Us or them?

Both.

(playful music) (laughter)