September, 1940. With London having endured the Blitz for nearly a month, people are calling for vengeance, but once again the night heralds more destruction. In Custom House, anxious residents dutifully head to the nearest public air-raid shelter as the warning siren wails. When dawn brings the all-clear, people disperse, but one man remains - he is dead, stabbed through the heart. Detective Inspector John Jago discovers that the victim was a pacifist. But why, then, was he carrying a loaded revolver in his pocket?