Season 01 Episode 04

The episode opens with a war flashback in a wood, with Sidney and a young comrade surveying the aftermath of a battle before gunfire breaks out and the comrade is hit. The flashback is returned to later in the hour. In Grantchester a house is on fire in the early hours. Sidney and Ben Blackwood get Marion Taylor out of it, and Marion had been sitting in the burning room and did not want to leave. Her husband Dominic thanks Sidney and then, at the end of Sidney's sermon, tells him the fire was no accident, and is interrupted by his wife before he can say more. Hildegard Staunton returns to Cambridge and visits the vicarage, where Mrs Maguire, who has not forgotten the war, is rude to her and is told off by Sidney.

Dominic Taylor is found stabbed to death in central Cambridge, near a public lavatory used by men meeting men. Sidney takes his suspicions there and the police arrest several men. Tobias Hall, the publican, admits he had been blackmailing Dominic, who was gay, and that Hall's note is what Marion burned, starting the fire. Hall names Ben Blackwood as Dominic's lover and warns Sidney that exposing the blackmail would expose Ben. Sidney tells Geordie anyway.

Geordie is unavailable for much of the case. His baby son has whooping cough and may die, and he is drinking and taking his temper out on his junior, DC Atkins, who is running the investigation and wants the vicar nowhere near it. Sidney's own conduct is questioned, because Ben Blackwood is arrested for gross indecency and the Blackwood house is daubed with the word queer. The murderer is Ben's father, Vic Blackwood, who killed Dominic to protect his son's name, and Ben has already confessed to the killing himself by the time Sidney works it out. The knife is recovered from the public lavatory. The episode ends with Geordie's son recovering and Sidney baptising him, giving the boy his own name as a middle name, and with Sidney at the piano with Hildegard. Sidney has asked Leonard, who is himself closeted, what vanity drives him to interfere, and has concluded that he has made a mess of things.

The episode is the first of the four Runcie stories to be told as a murder investigation rather than a puzzle, and it places the blackmail at the centre rather than the killing, because the death follows from a crime that the law itself treats as a crime. The public lavatory arrests are the point at which the series says something about the period that the novels leave largely alone, and the house daubed with the word invites the audience to look at what the police are doing in the same hour.

Sidney's interference is the other half of the episode, since he is told by a man with a dying son that he has no business in the case, and he goes on anyway. His treatment of Hildegard at the vicarage is the first time the series shows that his kindness and his selfishness operate at the same time, and Mrs Maguire's rudeness to a German widow is given no apology.