Season 07 Episode 01

It is the summer of 1959 and wedding season in Grantchester. Will Davenport is marrying couples in number, and one of his brides-to-be is Adele Fitzgerald, who lives at the declining Fitzgerald estate with her sister Maude. Geordie Keating is living at the vicarage, in Leonard's old room, growing Cathy's favourite flowers to win her back after she threw him out at the end of Series 6.

Will goes to a jazz club with Geordie, dances with a woman who leaves before he can learn her name, and is smitten. The next day the estate opens its swimming pool to local children and Geordie and Will take the Keating children, and Maude, who spends the day keeping children out of her garden, calls for help: a man is dead in her shed, apparently crushed when a brick wall collapsed on him. Geordie's new superior, DCI Elliot Wallace, assigns the case to Larry Peters and dismisses Geordie because it is his day off. A post-mortem gives heart attack as the cause of death, and the dead man is Edmund Fitzgerald, Maude and Adele's brother, who has lived an itinerant life abroad since the war. The Fitzgerald money passes only to men, who have also tended to have weak hearts. Geordie keeps working the case anyway and is given paperwork as punishment, since Wallace does not want him ruining Larry, and Miss Scott asks a friend at the post office for Edmund's recent telegrams.

Edmund had wired his sisters in January asking for money for a flight home, and they replied they had no funds. He had also wired Irene Gibbons, saying he still had the ring if she was interested. Irene explains that she and Edmund were as good as engaged until he went to war, that she wrote to him throughout, and that he cut off contact when it ended. She says she never sent the love letter found in his pocket and that it was kept in a jewellery box he had made for her, and a ring for her is now inside the box. Mrs Chapman suggests they look at Irene's father Frank Gibbons, a handyman, after Edmund was seen crossing the field between the Gibbons house and the estate, and they find Edmund's rucksack with a first-class train ticket bought in Mayfair, where Adele's fiance Howard lives.

The pieces are these. Edmund came to Irene's house, climbed through the window as he had when they were young, found the letter and left the ring. Irene's father, who disliked Edmund and thought his daughter would be ridiculed for marrying into an aristocratic family, had been intercepting their letters during the war, and he found Edmund in the house and threw him out, which Irene saw as a struggle without recognising Edmund. Adele's engagement is a matter of necessity rather than love: Howard is a fifth cousin of the Fitzgeralds, the last male of the line, and the sisters have no money. Adele answered Edmund's January telegram from a different post office, sent congratulations and a ticket home, and sold a painting to pay for it.

The solution is that the sisters poisoned Edmund with hemlock from Maude's garden and staged his body as the victim of a fall, the bruises he took in the encounter with Frank Gibbons giving them the story to tell. They brought him home in June because that is when Maude's hemlock was ready, and they killed him because Edmund's own marriage would have turned them out of the house. Maude's plan went further: Howard was to die after the wedding of a hemlock-induced heart attack, leaving the fortune with Adele. Both sisters are arrested.

Two threads carry forward. Leonard is about to open a beat poet cafe with an investment from Jack, and Mrs Chapman has imposed her own decorations over his plans, takes offence when he disagrees, then relents and lets him decorate as he wishes. Geordie gives Cathy, at the cafe opening, the flowers he has been growing for her; they are not her favourites, and she tells him he is always late for the children, forgetful and blind to the work she does. Will, meanwhile, is infatuated with the woman from the jazz club, who turns out to be Wallace's fiancee, has already found him at the vicarage and slept with him, gives him her name, Maya, and tells him they cannot be together.

The episode resets the programme with a new superior officer and a new vicarage arrangement, then runs a country house murder in which the money is the whole motive and the family's only inheritance is a heart condition. The hemlock is the strongest single detail, because a garden plant becomes the murder weapon and the timing of the killing is fixed by when it was ready to cut. Adele's telegram is the fact that undoes the sisters' account of themselves, since the same women who said they had no funds paid to bring their brother home in order to kill him.