Klop ('Bedbug') Ustinov (1892–1962) was an MI5 secret agent tasked, not with killing, but with bemusing and beguiling his enemies into revealing their deepest, darkest secrets. Through the Russian revolution, two World Wars and the Cold War, Klop bluffed and tricked his way into the confidence of everyone from Soviet commissars to a Gestapo Gruppenführer. Journalist Peter Day tells the epic tale of an agent whose missions remained obscured by his socializing and womanizing.