DCI John Barnaby arrives in Midsomer with his dog, Sykes, and Harriet Wingate, headmistress at upmarket Darnley Park Girls School, soon asks him to patrol their forthcoming classic car show. Jones, a car enthusiast, wants to help but Barnaby is unused to locals asking favours.


Jones feels wrong-footed by his new boss, but Barnaby is intrigued when he learns that the remains of famous racing driver Duncan Palmer were discovered at Darnley Park - 40 years after he was thought to have drowned in the Lake District.


Harriet is fighting a challenge by school governor and parent Jamie Cameron to turn Darnley Park into a state school to rid it of debt. Unbeknown to Jamie, Harriet has invited his ex-wife Kate - along with her father, racing legend Peter Fossett - to the show. When Kate arrives, she has a secretive talk with her daughter Charlotte, a pupil there.


Fossett is annoyed that his fellow judge is club DJ Dave 'Doggy' Day, who knows nothing about cars. But Doggy volunteers with Harriet's daughter Jessica at local council estate Moor Park. The police question Thomas Brightwell, an estate youth who has been spotted loitering at Darnley.


Charlotte orders her 'angels', boarders Nerys and Bethan, to deliver a screwdriver to Thomas. Doggy tries to start Kate's vintage Hispano and is shocked to see Charlotte whom he knows from the club scene. Later he is crushed by the crank handle and killed.


It's murder, not an accident, but Kate seems more upset that something has gone missing from her car. Jamie cheers up Jessica with a sly grope and she tells him her mother is trying to oust him from the board and appoint Kate. Barnaby thinks Nerys and Bethan's video diaries could hold clues. He's also convinced that the death of Duncan Palmer at the school is more than a coincidence.


Despite revelations about her affair with Jamie, Jessica bullies her mother into retiring, while Charlotte heads for the West End clubs. Thomas doesn't arrive to pick her up and the next day he is found dead at the wheel of his expensive classic Riley.


With the help of some classic car magazines, Barnaby guesses the true identity of Jessica's father and realises there could be more family connections. Charlotte is arrested in London for selling cocaine and the detectives uncover a drugs ring involving Kate and Thomas.


But they still don't know the murderer's identity - until Barnaby goes to meet someone at the barn where Duncan Palmer met his death. When the killer turns on him, could his first case also be his last?