The engagement of effervescent Mally Lee to handsome, well-connected Roger Mooring is not going well. They quarrel constantly and Mally's idea is to spend time apart and delay the wedding. She has no money of her own and hopes to find a job, which materializes when Sir George Peterson hires her to be a governess to his daughter. She happily heads to London and all is well until Sir George and his odious secretary, Paul Craddock, accuse her of the theft of a diamond brooch and an important paper. When the jewelry inexplicably turns up in Mally's possession, the two men threaten prison if she doesn't return the paper.

It's difficult to imagine a damsel in more distress than Mally Lee as she makes a daring escape. Having no idea where the mysterious paper is or what it contains, her only recourse is to run. Roger proves to be of no help, and as she battles the icy wind and rain, the menacing detective sent to find her, the London streets, and ultimately, the quieter countryside (which provides its own perils) Mally realizes she must depend on the kindness of strangers she meets on the way.

Patricia Wentworth fills her story with a highly entertaining cast of characters who assist and impede her plucky heroine as she races to find a solution to the mystery and her own freedom.