Semi-retired sleuth Molly Morgenthau Babbitts goes undercover as a governess to investigate a robbery at the aristocratic Janney mansion on Long Island. Before Molly can crack the case, a more shocking crime is perpetrated and more mysteries develop, presenting a baffling jumble of clues for Molly to unravel. At the center of the intrigue is Esther Maitland, the family's competent but mysterious private secretary. What is she hiding? Is she really as trustworthy as the family believes she is?