On 10 May 1941, Rudolf Hess, then the Deputy Fuhrer, parachuted over Renfrewshire in Scotland on a mission to meet with the Duke of Hamilton, ostensibly to broker a peace deal with the British government. After being held in the Tower of London, he was transferred to Mytchett Place near Aldershot on 20 May, under the codename of 'Z'. The house was fitted with microphones and sound recording equipment, guarded by a battalion of soldiers and codenamed 'Camp Z'. Churchill's instructions were that Hess should be strictly isolated, with every effort taken to get any information out of him that might help change the course of the Second World War. During the ensuing months a psychological battle was waged between intelligence officers using the new Freudian techniques of 'dynamic psychologies', and he man who had been a heartbeat away from Hitler. Stephen McGinty uses documentation, contemporaneous reports, diaries, letters and memos to piece together a riveting account of the claustrophobia, paranoia and high-stakes gamesmanship being played out in an English country house. CAMP Z is a 'locked room mystery' where the 'locked room' is a man's mind that no one can conclude, with any degree of confidence, is sane.