Season 04 Episode 02

Violet Todd has gone back to Alabama and Sidney is drinking heavily. He wakes on the vicarage couch with no memory of the night before and no coat. Mrs Chapman threatens to take the matter to the archdeacon and Leonard offers to listen. A young woman with a puncture wound in her neck, found in the street outside a slum house near the Kite, asks for Sidney by name in hospital and dies before she can say more. He had asked her for a light the night before, and remembers nothing else.

Sidney's jacket is found in her room. The women in the house claim to be seamstresses, and they are prostitutes, and the jacket's pocket holds a book of matches from Patsy's Club. The dead woman was Sadie Parker. The house and the club are both owned by Rupert Simpson, who is out golfing with Archer Davis, a councillor. Simpson dismisses the police, and Sidney loses his temper with him anyway. Sidney runs into Violet again: she is waiting on her brother Charles's death certificate before she leaves, and he takes her punting and then to the slum, where an enforcer, Rory Dale, has turned the women's furniture out into the street and is threatening them. Sidney fights him and is losing until Violet hits Dale with a piece of wood. Geordie stakes out the house, closes the club and finds an account book showing Simpson making regular payments rather than taking a share, which suggests someone above him.

The photographs on Simpson's office wall show him and Davis with a series of women all wearing the same necklace, and Sidney remembers Sadie wearing it. Simpson admits he was with Sadie that night, and that she lost her temper when he called her a cab, which Sidney understands as her realising she was one of many. Dale then walks into the police station and confesses to running the prostitution and to the killing, plainly covering for Simpson and Davis. Outside the police station after a row, one of the women, Ava Holmes, tries to kiss Sidney, and he pulls his hand away and the ring she is wearing cuts him. The mark matches the wound on Sadie's neck. Sadie had told the women about the photographs and wanted to speak out, and Ava, who could see no way out and feared reprisals against all of them, strangled her to stop her. The other women then agree to testify against Davis, showing Geordie the cigarette burns he has given them, and Davis is arrested as the man behind the operation.

Sidney asks Violet to stay and she refuses, so he tells her he will go to America with her. Mrs Chapman and Leonard try to talk him out of it and send Geordie, who understands that the decision is made. Sidney gives Geordie a piece of needlepoint reading abhor what is evil, hold fast to what is good, preaches his last sermon in Grantchester, and plays one last game with him over a pint.

The episode is Sidney's last and its case is arranged around what a man does when he has stopped caring, because the detective is drunk through the investigation and the solution arrives through a scratch on his hand from a woman who was trying to kiss him. Ava's motive is the strongest writing in the episode, since the woman who kills to protect the others is the one with no way out, and the cigarettes burns the police are shown in the last act are the detail that turns a confession into a case against the councillor. The ending is deliberately unresolved in one respect, because the series does not show Sidney leaving and the next episode begins with him gone.