Alphy and Geordie investigate witchcraft at a home for orphaned and disadvantaged children run by Alphy's old friend. When a body is found, Alphy struggles to consider his friend as a suspect.

There’s no shortage of murder, mystery, and mayhem in the seemingly quiet 1950s Cambridgeshire village of Grantchester—and police detective Geordie Keating (Robson Green) and the resident vicar (played by James Norton, Tom Brittney, and Rishi Nair, respectively) are always on the case. There’s a real warmth to this period crime drama, set in a picturesque location with central characters who’ve formed their own version of a family.

In Season 10, Alphy’s really found a home in Grantchester. In Geordie too, he’s found a best friend and his intellectual equal. Love proves more elusive, until a case throws him in the path of a romance. But before he can let anyone else in, he must confront truths about himself. Geordie, meanwhile, wrestles with his expectations for his own son and Cathy takes steps to better her career with the help of Mrs. Chapman.