Wimsey's mother, the Dowager Duchess of Denver, telephones to say that Thipps, an architect hired to do some work on her local church, has just found a dead body wearing nothing but a pair of pince-nez in the bath in his London flat. The official investigator, Inspector Sugg, suspects Thipps and his servant; Wimsey starts his own enquiry. Sir Reuben Levy, a famous financier, has disappeared from his own bedroom, and there has been a flurry of trading in some Peruvian oil shares. Inspector Parker, Wimsey's friend, is investigating this.
The corpse in the bath is not Levy, but Wimsey becomes convinced that the two are linked. The trail leads to the teaching hospital near the architect's flat, and to surgeon and neurologist Sir Julian Freke, who is based there. Wimsey discovers that Freke murdered Sir Reuben and staged his 'disappearance' from home, having borne a grudge for years over Lady Levy, who chose to marry Sir Reuben rather than him. He also engineered the trading in oil shares, to lure Sir Reuben to his death. He dismembered Sir Reuben and gave him to his students to dissect, substituting his body for that of a pauper donated to the hospital for that purpose, who bore a superficial resemblance to Sir Reuben. The pauper's body, washed, shaved and manicured, was then carried over the roofs and dumped in Thipps' bath as a joke. Freke's belief that conscience and guilt are inconvenient physiological aberrations, which may be cut out and discarded, is an explanation for his conduct. He attempts to murder both Parker and Wimsey, and finally tries suicide when his actions are discovered, but is arrested in time.
