A suspicious suicide note has Barnaby wondering if foul play was involved in a young woman's death.

Julian Shepherd, who has most of his money invested in Charles Edmonton's new invention, is found drowned, and there is every appearance that he killed himself due to money problems. Then a villager who has been stealing peregrine falcon eggs from Charles's widow is also found dead, and Barnaby and Troy investigate.

The Barnaby-Troy partnership is about to come to an end, as Troy has passed his inspector's exam and is moving on. However, the murderers of Midsomer go on piling up the bodies. Joyce Barnaby gets trapped in a fallen canal tunnel, and in getting her out seven skeletons come to light in a hidden chamber. Meanwhile, two local tearaways are shot dead in the woods at Midsomer Worthy, and a tramp called Tom is accused of the killings. While Troy looks into the shootings, Barnaby wrestles with an old mystery. And although six of the skeletons found in the tunnel date from the 18th century, one is much more recent.

Jean Wildacre dies suspiciously during a performance as assistant to local magician Aloysius Wilmington, and Barnaby & Jones are called in. They have to investigate the relationships of Midsomer's Magic Circle, a group of old friends whose activities spun off a new cult, and led to long-running animosities. Soon they are looking for colorful South American poison-dart frogs, as the death count rises