The community of Shipton Abbott is rocked when a beloved painting disappears in a seemingly impossible heist. Humphrey tries his best to find some common ground with Archie.

Humphrey and the team face one of their strangest cases yet when a dead man is found in the centre of a crop circle. Meanwhile, Martha faces her own professional challenge as her café is visited by a food critic. With Archie's help, she rises to the occasion, but in doing so, misses an important IVF appointment with Humphrey.

Panic spreads throughout Shipton Abbott when an arsonist targets three local businesses, scrawling 'PIG' at the scene of each fire. Humphrey and the team are baffled until they realise the fires follow an unusual pattern by invoking the Three Little Pigs fable. Meanwhile, Martha is in turmoil over what happened with Archie.

[Season Finale] Reeling from Martha's decision, Humphrey must pull himself together to solve an inexplicable crime. A house was burgled and all forensic evidence points to one suspect. The only problem is that this suspect was locked up in the station's police cell at the time of the break-in. Meanwhile, Martha is equally distraught in the wake of recent events.