Walking home late one night, Commander Dalgliesh discovers the body of Hilary Robarts. The killing has all the hallmarks of the Whistler's work but this is now the second woman from the nuclear plant to be killed. Ryan Blaney was out walking at the time and doesn't have much of an alibi. Likewise, Caroline Amphlett, another plant employee, pressures a colleague to provide her with an alibi. As Chief Inspector Rickards questions the dead woman's colleagues and acquaintances, Dalgliesh learns that Toby Gledhill has disappeared.