Originally published in 1935 by Hodder & Stoughton.

Flossie Palmer worked in the kitchen at 16 Varley Street. It was her job to see that the trays were carried up to Miss Rowland on time. But the job lasted only a few hours and Flossie found herself running, her heart pounding in her throat, down the foggy street, not daring to stop or to listen for the footsteps that might be following her. She had been exploring the drawing room of the great house and had suddenly seen the big six-foot mirror move - and reveal a human face. In the thickness of the fog Flossie met Miles Clayton and told him her story. Miles has a story of his own which explains his presence in London - searching for a 19-year-old girl who, if found, would become heir to a vast sum. How these two mysteries coincide, and how they are resolved, form one of the author's most beguiling adventures.