Nancy receives a letter meant for a British heiress who has the same name and, in her attempts to contact the other young woman, faces danger from a man who operates a Lonely Hearts Club mail fraud.
Despite warnings from a stranger, Nancy sets out for France to search for a flight of 99 steps which may help solve the mystery of a weird dream and a possible case of blackmail.
After a near disaster, when the boat Nancy and her two friends were in gets caught in a horrible storm, a mystery unravels in a bungalow that they have found.
