In the first episode, Kitty Trevelyan tries to put the troubles of her past behind her as she joins two other girls, Flora Marshall and Rosalie Berwick, to volunteer at one of the busiest war hospitals in Northern France. For the hospital workers, it’s a daily battle to keep the war machine churning. Volunteers are desperately needed, yet there are some who see these women as a threat.
The volunteer nurses settle into life at the hospital. Despite struggling with some personal problems, Kitty throws herself into her work, helping her new patients, Major Crecy and Private Byeford. Meanwhile, the hospital readies for a convoy of new patients.
Thomas wrestles with a growing attraction to Kitty, and Joan reveals a dark secret to one of her patients. While Thomas may not be prevailing with Kitty, he is having success on the wards with a pioneering wound irrigation system.
As the hospital staff gather at a funeral for some of the patients, Joan is in agony not knowing whether her fiancé is alive or dead. Joan’s spirits are lifted by the arrival of 13 Tommies, known as "The Lucky 13," from her hometown of Liverpool. Thomas seizes his opportunity to pursue Kitty, but when she gets a shocking summons to meet with a mysterious figure from home, it’s Miles who comes to her aid.
Colonel Ballard would rather be with his men than at rest within the calm sanctuary of the wards. Yet, when Grace reveals knowledge of Punjabi and an upbringing in India, the Colonel is temporarily calmed. However, another soldier, Private Gorman, seems focused on riling him further.
Joan is hauled up on a charge of aiding the enemy and faces a possible lifetime in prison. Her actions send ripples through the hospital. Kitty’s wracked with guilt, for she knew about Joan, but didn’t try to stop her. Flora discovers Peter’s brother, Jimmy, and happily reunites the siblings; but, Peter has a difficult decision to make.