Nigel West"s book traces the history of MI 5 from its modest beginnings in 1909 until 1945. The focus is on its role in WW II, recalling the enemy agents rounded up in Britain; the manipulation of the Axis espionage networks by the use of "turned" Abwehr agents and the all-important check on its success provided by the intercepted German signals decoded at Bletchley. Laced with true anecdotes as bizarre and readable as espionage thrillers, this book is based on interviews of Nazi and Soviet agents, counter-intelligence officers, case officers and, most remarkably, more than a dozen of the double agents.