Gated estate Challis Court is a tight-knit community for retired police officers, but when a new arrival is found dead, the other residents regard the murder as an affront; Barnaby realizes that the killer is likely an ex-police officer. Guest stars include Tom Conti (Oppenheimer, Doc Martin).

The town of Causton's detective chief investigator and his detective sergeant investigate the scandals and deadly deeds that lurk just beneath the well-manicured surface of the county of Midsomer. The series is bolstered by a rotating cast of investigators and many special celebrity appearances.