A musical comedy directed by Monty Banks. A cook recalls a night spent in a French estaminet in 1915.

Courtenay John Dayre is drugged by a jealous spy on the night before his loveless marriage to Anthea. His twin, John Courtenay Dayre, reluctantly agrees to impersonate his brother at the wedding, only to discover a genuine affection for his accidental wife. Meanwhile, Courtenay begins to understand the price of things when he realises that his affair has allowed a valuable military secret to be stolen.

Facing an arranged marriage to a man of dubious morals, heiress Korah Hurley poses as the impoverished travelling companion of her aunt, the Marquise de Jaurmais, in order to test whether her rakish fiancé's affections are truly for her or for the fortune she will inherit.