American GI Ernie Williams, admittedly weak-kneed, has an uncanny resemblance to British Colonel MacKenzie. Williams, also a master of imitation and disguise, is asked to impersonate the Colonel, ostensibly to allow the Colonel to make a secret trip East. What Williams is not told is that the Colonel has recently been a target of assassins. After the Colonel's plane goes down, the plan changes and Williams maintains the disguise to confuse the Nazis about D-Day.

Danny Kayeas Ernie Williams
Dana Wynteras Margaret MacKenzie-Smith
Wilfrid Hyde-Whiteas Colonel Somerset
Margaret Rutherfordas Lady Vivian
Diana Dorsas Bridget Stanhope
Allan Cuthbertsonas Captain Patterson
Jesse Whiteas Joseph Praeger
Gregory Walcottas Rock Houston
Terence de Marneyas Colin Twickenham
Rex Evansas Carleton Brown Wiffingham