Another homeless man is found dead and killed in the same manner as the previous victims. Geordie and Will realize that they may have sent the wrong man to prison, and the real killer may still be at large.

The series picks up in the long hot summer of 1959 with wedding season in full swing in the Cambridgeshire village of Grantchester. Starring Robson Green as Geordie Keating and Tom Brittney as Will Davenport.