The police investigate the apparent suicide of Julian Shepherd who drowned after driving his car into a nearby river. Shepherd along with several other local residents had invested money in Charles Edmonton's latest invention, a fuel-less transportation system. Edmonton, despite his advanced years, instilled a good deal of confidence in his investors but Shepherd was facing severe financial difficulties and urgently needed his investment to be returned. Troy meanwhile finds himself working with the comely PC Sarah Pearce who, as a wildlife liaison officer, is investigating the illegal sales of birds of prey and their eggs. The two cases come together when a birds' egg collector is found dead after a visit to the Edmonton estate. As the number of dead bodies begins to climb, Barnaby realizes that there is something far more sinister at play.