Run time: 128 mins

Although Major William Martin’s body washed up on the southern Spanish coast in 1943, the man himself never actually existed. He was, in fact, a figment of a team of British Intelligence officers’ imagination and part of what became known as one of the greatest deception operations in military history: Operation Mincemeat.

Based on Ben Macintyre’s book of the same name, here John Madden (previously known for Shakespeare in Love and The Best Exotic Marigold Hotel films) tensely traces Operation Mincemeat from conception to completion.

When Ewen Montagu KC (Colin Firth) announces his retirement the night before his wife and children depart for America without him, his brother Ivor (Mark Gatiss) suspects he has a new, covert occupation lined up. Indeed, Ewen has been hired by British Intelligence to assist with a ploy to deceive the Nazis of the location of an impending invasion.

With family-friend Hester Leggett (Penelope Wilton), the resourceful Jean Leslie (Kelly Macdonald) and meticulous Charles Cholmondeley by Ewan’s side it seems to be a winning combination. That is until conflicts of personal affections and egos, combined with pressure from their superiors Admiral John Godfrey (Jason Isaacs) and Churchill (Simon Russell Beale), threaten the success of their plan.