Devington Manor in Midsomer is hosting a music school led by the internationally renowned pianist Sir Michael Fielding. Among the nervous students hoping to win a place on his 'master class' are shy prodigy Zoe Stock, talented musician Francesca Sharpe, handsome but vain Orlando Guest and ambitious Benedict Marsh.


Zoe suffers panic attacks, and after finding Orlando and Francesca together, runs off to the river. To her horror, she witnesses a woman drowning, leaving a baby on the banks. But when Barnaby and Jones arrive, there is no sign of the woman or her child.


Barnaby is struck by the similarity to another drowning at the same spot 20 years ago, but Sir Michael's daughters Miriam and Constance don't seem to recall much about it.


At the concert, Francesca's pushy father Simon and Orlando's voluptuous mother Penelope compete for Sir Michael's attention, while Terry and Dawn Stock just seem bewildered by Zoe's talent. Benedict is angry when he fails to reach the master class and lashes out at Sir Michael. Meanwhile, Rev Gregory, rector of nearby St Cecilia's Abbey, invites Zoe to play the organ at Mass.


Jones discovers that Rev Gregory reported the first drowning but he is unforthcoming and Barnaby is sure he's hiding something. As they leave the abbey, a pile of roof tiles comes crashing from the church tower. Was Zoe the target?


Back at the pub, Zoe sees a picture of her drowning woman, although the photo dates back to 1990. Petty criminal turned landlord Jonas Slee explains it is Mad Molly, who lived in a shack in the woods. Barnaby takes Zoe there and it seems strangely familiar to her. But her father claims she is fantasising due to shock.


While Barnaby returns to the shack and finds some old medicine, Orlando tells Zoe he loves her and begs her to meet him in the woods that night. But when she gets there, Orlando is hanging, dead.


Bullard reveals the medicine is a treatment for hallucinations and paranoia. The police search for Benedict while Rev Gregory's secret suspicions are confirmed. He summons Zoe's parents but when they arrive, the cleric's throat has been cut.


Jones finds results of a DNA test at the abbey, while Terry and Dawn tell a stunned Zoe that she is adopted. Barnaby discovers she is Molly's daughter and was hidden at the abbey until she was adopted illegally. Returning has triggered long-buried memories.


The truth about Zoe's father turns out to be even more shocking. As the police race to Devington Manor, can they stop Zoe following in her mother's tragic footsteps?