DI Purbright and DS Love investigate the disappearance of a Mr. Hopjoy after receiving an anonymous letter saying the man had disappeared. The search of his house reveals a number of suspicious elements including blood and a carboy that once contained acid. As they look into his background, they learn that he was frequently absent for days at a time and was, to put it mildly, a libidinous fellow. He lodged with Gordon Periam, a tobacconist who, the pipe smoking Purbright notes, doesn't smoke. Periam is missing however, as is Hopjoy's car. While the results of the forensic examination of the house is still outstanding, Purbright learns from his Chief Constable that Hopjoy was something of a spy and that two of his colleagues, Tozer and Barraclough will be conducting their own investigation. (thetvdb.com)