When a headless horseman makes an an appearance at Quitewell Hall it foreshadows a number of deaths amongst an aristocratic family. Whilst a Civil War re-enactment takes place the family relive their own historic battles with their neighbours.

After convicted killer Grady Felton returns to his childhood home after 18 years, it causes anger and raw emotion for the family of his victim. A barrister who was involved in the trial is murdered and the finger of suspicion is pointed at Grady. Grady has an alibi though so the detectives suspect he could be working with an accomplice. Grady ends up being critically injured in an arson attack and it looks like somebody is out to settle some old scores. Meanwhile, Barnaby must face some personal demons of his own as he tries to train for the Chief Constable’s fitness test.

After having been in a coma since the night she attempted to elope, Harriet Farmer wakes up. A killer then murders members of a local chess club. John Barnaby and the team investigate whether the attack which left Harriet for dead a year ago could be linked to moves on a chess board and atempt to find out what happened to her boyfriend Finn.

The murder of a journalist leaves reminders of a 1960's horror movie starring Midsomer’s Stella Harris. After Stella’s more famous sister returns following a 40-year family rift, the killings contiue, each reminiscent of a film plot.

A woman ends up being crushed to death with a giant wheel of Midsomer Blue cheese. Secret and controversial plans to modernise the dairy end up being revealed as rumours about the private lives of the parents cause a row at a local prep school. More people linked to the dairy are involved in shocking deaths as long-held secrets begin to be revealed.