Clifford Bentley is released from prison and is welcomed home with a party. His sons are divided: John Bentley is busy preparing for the impending heist, while David acts distant and neglects his responsibilities. He broods over a photo of Julie-Ann.
Things are tense between Bradfield and Tennison as rumors fly about their relationship. Bradfield considers getting Tennison transferred, but she insists on staying at Hackney Station.
Mr. and Mrs. Collins are questioned about their daughter’s death. Mid-interrogation, Tennison gets a tip: a neighbor saw Eddie Phillips at the Collins house two nights earlier. Mr. Collins admits that this is true, and that both Eddie and Julie-Ann asked for money for a deal they had made with “Oz.”
There’s a breakthrough in the case when the detectives realize that although both Eddie and Julie-Ann were recently injured, their injuries happened on different days. A golf club stained with blood and hair is found in the Collins home. Mr. Collins confesses that he locked his daughter in the room at her request, as she tried to get clean. She escaped the room and had a violent episode, and when she tried to steal money he hit her with the golf club. Mr. Collins claims that his wife was at her sister’s house during these events, but Bradfield points out that Mrs. Collins’ sister denies seeing her that day. Mrs. Collins’ fingerprints are found on the golf club, prompting her to finally confess to assaulting Julie-Ann. Eddie Phillips knew about the assault and approached the Collins’ to blackmail them. The beating was not fatal, however, so Julie-Ann’s killer is still on the loose.
The detectives turn to the victim’s purse for clues. They find a note about “Tod,” similar to entries from drug dealer Dwayne Clark’s sales log. According to the log, Clark interacted with “Tod” the day Julie-Ann died. Tennison realizes that “Tod” could be an acronym for “Teresa O’Duncie,” the nurse from the drug dependency center who let Julie-Ann use a hospital phone.
When the detectives question O’Duncie again, they make a shocking discovery: she is the sister of mysterious drug supplier “Oz,” aka Terence O’Duncie. The detectives raid Oz’s address and arrest him and everyone inhabiting the house. When Oz tries to bribe the officers, Gibbs gets excessively physical. Tennison watches in silence, shocked.
Eddie Phillips is found dead in a canal. His autopsy reveals that he died from internal bleeding, not drowning, and that rat poison was found in his system. Meanwhile, money found on his person matches the serial numbers of a withdrawal from Mr. Collins’ account.
The detectives interrogate Oz, suggesting that he killed Eddie because Oz knew he had talked to the police. Oz claims that he doesn’t know Julie-Ann, and upends the conversation when he accuses Gibbs of assault. His complaint is strengthened by a testimony from Flowers, a young woman who lived in the house. Tennison is asked to give her side of the story, and gently pressured by her colleagues to cover for Gibbs.
Tennison questions Flowers, who remembers seeing Julie-Ann pay Oz, and confesses to witnessing Eddie’s death. Despite the evidence mounting against him, Oz continues to deny killing Eddie and Julie-Ann.
Tennison gives a statement that reflects positively on Gibbs, lying about what she saw. Gibbs is cleared of charges and Jane’s colleagues are grateful to her. Buoyed by her newfound comradery and frustrated with her mother’s disapproval, Tennison moves into police housing. Bradfield visits her new apartment and the two spend the night together.
The next day, Tennison is given an unusual assignment: to follow-up with conspiracy theorist Ashley Brennan, who monitors radio waves from his flat. He has submitted several tips about suspicious walkie talkie chatter, which we realize is from the Bentley heist preparation. The audio triggers Tennison’s suspicion, but her colleagues dismiss Brennan as mentally unstable.
Tennison and Sergeant Harris visit Flowers in the drug dependency hospital. As they leave, Tennison recognizes the man who acted suspiciously during the house-to-house—who Harris identifies as John Bentley. Tennison is convinced that the voice she heard on Brennan’s audio recording belongs to John Bentley.
On their way back from the hospital, the Bentley brothers visit a storage locker. We see a green beaded necklace on the floor which matches Julie-Ann’s bracelet.