In the cemetery of Nuestra Señora de la Soledad de Huelva there is a tombstone that reads: «To Glyndwr Michael, DEP. He served as William Martin in the 'Royal Marines'. This is their story, or rather the story of the men and women of the British intelligence team (the Committee of Twenty) who hatched a harebrained plan to convince Hitler that the Allies would invade Greece instead of Sicily.

Ronald Neame already brought this operation to the screen in 1957, taking as a reference the book written by one of its protagonists, Lieutenant Commander Ewen Montagu, and now John Madden does the same with the adaptation of a text by Ben Macintyre that consolidates investigations previous ones and adds a breath of fiction to twin them with the rhythm and emotion of classics such as 'The 39 steps', by John Buchan. The result is not a groundbreaking spy movie, but the craftsmanship with which Madden builds a narrative that works like clockwork is appreciated. The interventions of Churchill, a false love triangle and the power struggles within the British War Office serve as parallel plots so that the main line of the story takes air and comes alive until the end pushed by an excellent collection of interpreters who they fit like a glove into the rugged psychologies of their characters.