It’s 1955 in Grantchester, local vicar Sidney Chambers [James Norton] meets with the new archdeacon, Gabriel Atubo. Acknowledging that Gabriel’s predecessor was dispatched under some controversy and embarrassment, Gabriel questions whether he can rely on Sidney to rebuild trust in the church and lead by example. Sidney reassures him he can be counted on.
Before the night is out, Sidney is on the dance floor with his old flame Amanda Hopkins [Morven Christie. Whilst they close in for a kiss, Sidney’s best friend DI Geordie Keating [Robson Green] sits nearby with wife Cathy [Kacey Ainsworth], the spark a little dimmer in their own relationship.
The next day Sidney accompanies Geordie to The Round Church in Cambridge, where an elderly man, Dr Terrence Atwell, lies dead. Whilst being pestered by church caretaker Mr Harland, Geordie tells Sidney about the victim; Dr Atwell ran a soup kitchen for the homeless. On closer inspection of the body, it appears Dr Atwell died by drowning. But how does a man drown in the middle of a church and is this connected to a series of murders targeting respected figures in the community?
Amanda gets a letter from estranged husband Guy [Tom Austen] saying he wants to see his daughter. Sidney can’t contain his frustration; Guy didn’t care when Grace was born. He’s clearly trying to control Amanda. But Amanda reassures him that she won’t let Guy take Grace away.
As Geordie and Sidney get closer to the truth behind the murders, Sidney is forced to confront the conflict between his relationship with Amanda and his calling as a vicar, and the fact that he and Amanda must face Guy, but will it be together or apart?