England, 1944: an audacious attempt on the life of the British high commander General Sir Lawrence MacKenzie-Smith by German intelligence sparks a search for a convincing lookalike. American Danny Kaye as Pvt. Ernie Williams, a gifted mimic who bears a striking resemblance to MacKenzie-Smith, is chosen to play the double. When Ernie is presented to MacKenzie-Smith as his proposed double, the General — after some initial hesitation — agrees to the plan. Yet the crucial detail, that Ernie will serve as a decoy for German intelligence, is kept from him, setting the stage for a tense, high-stakes game of deception.
The mission quickly thickens as Lady Margaret MacKenzie-Smith returns early from a war-bond tour in Canada to seek a divorce, exhausted by years of neglect and the General’s womanizing. Lady Margaret Dana Wynter recognizes Ernie as an impostor almost at once, but out of necessity she becomes part of the ruse. She shares intimate, behind-the-scenes details about MacKenzie-Smith to help refine Ernie’s disguise, and, as their cover deepens, a fragile bond blossoms between them, turning into something warmer than either expected.
German intelligence does not ease up. When Ernie attempts to step away from the ruse, he and Margaret discover that a plane carrying MacKenzie-Smith was shot down, leaving no survivors and forcing Ernie to press on in the role. After a wild regimental party, he is abducted by one of MacKenzie-Smith’s mistresses and a treacherous officer—both Nazi agents—and ferried to Berlin for interrogation. Unable to convince his captors that he is merely a decoy, Ernie blurts out details about non-existent invasion plans, which the Nazis seize as truth. Left alone, he manages to wrangle a list of German agents operating in Britain and uses it to engineer a dangerous escape from German Headquarters.
The chase takes a dizzying turn through a Berlin cabaret, where Ernie adopts a Luftwaffe pilot’s persona and boards a bomber bound for England, managing a parachute escape on the way. He is captured again and brought before General Carleton Brown Wiffingham [Rex Evans], a friend of MacKenzie-Smith, only to reveal—through the list he carries—that Wiffingham is, in fact, the chief Nazi infiltrator within the British Secret Service. The tension rises as Ernie realizes the danger he’s in and the betrayal that surrounds him; a swift rescue interrupts the doomed outcome that would have seen him silenced for espionage.
With the invasion moving forward, Ernie makes it back to London and, after the trauma and trials, is reunited with Lady Margaret. In a quiet, relieved exchange, they confess their love for one another, and the hope they share for a future beyond the war lingers over the city as the operation unfolds.
