Percy Winthram (Harry H. Corbett), a shy, repressed 39-year-old, is in London with some buddies to see the football championship. While on the town, his pals bet that he can't talk a beautiful blonde (Diane Cilento) into a tryst. Unknown to them, the lady in question is a prostitute. But after overhearing the wager -- in which Percy's motorbike would be forfeit if he loses -- she kindly takes him back to her apartment, regaling him with lies about her luxurious past life along the way.