Then barbiturates are stolen from Raif and Georgina Canning's veterinary surgery and the district nurse is found in her crashed car in a confused state. Barnaby and Troy dash to the Manor, fearing the drugs theft may be connected to the death threats - but they find Melissa is already lying dead by the swimming pool with a syringe in her stomach. Now they have a murderer to find.
Neville St Clair works in the City of London and is a man of very regular and respectable habits. One day, his wife goes into town for lunch and is shocked to see her husband in the window of an opium den. That evening, he fails to return home, and Mrs St Clair decides to consult Holmes.