DCI Barnaby and DS Winter are called in to investigate the death of Victor Karras, a manufacturer of exclusive board games, who appears to have been poisoned. Guest stars include Rachael Stirling (Detectorists).

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.