Teenager Danny Merrick thinks he's seen a ghost at Winyard, a creepy house in the woods near Midsomer Newton. His mother Anne tells house-hunters Caroline and Peter Cave that it could be just the remote cottage they are looking for.

Estate agent Harriet Davis won't let them view the house, claiming it's under offer. Then she tells owner Charlie Magwood, a Londoner who was evacuated to the house as a child, that she's had no interest from buyers. Undeterred, the Caves visit Winyard but they are spooked and flee, only to be garrotted with piano wire.

Scott is ill, so Barnaby persuades PC Ben Jones to help him with the investigation. Joyce, meanwhile, is helping Giles Cato and the Midsomer Conservation Group identify 'at risk' buildings in the area. Cato says he is prepared to kill to conserve.

Self-styled heritage experts Lesley and Barbara Flux show the detectives a bottled human heart they found in the hearth at Winyard, which they claim is a curse. They believe the house is protecting itself against developers.

Jones plants a tape recorder at Winyard and tapes a conversation between an old man and a young boy. During a visit to reassure pupils at the village school, Jones suspects Danny's younger brother Philip is the voice on the tape.

Cato is appalled when Joyce discovers local builder Gerry Moore has applied to extend Winyard, while Philip is confused when he sees Charlie at the Feathers hotel.

Lesley and Barbara tell Barnaby that Harriet has been selling off 'unwanted' houses cheaply to Gerry, in order to split the profits after he does them up. They promised to keep quiet in the hope of buying Winyard at a discount. Jones accuses Harriet of killing the Caves because they got in the way of her plans.

Solicitor Alan Harcourt tells Barnaby that the real owner of Winyard is Jack Magwood, Charlie's brother. He's in prison for murdering a policeman 18 years earlier but has gone on the run just three months before being released.

Barnaby rushes to Winyard to find Joyce there with Philip and Jack. Jack is arrested, but when Barnaby visits neighbour Grace Woodhall, he starts to unravel the true story of the Magwood twins. Then Harriet is found dead at Winyard&ldots;