Bank manager John Hornbury is missing, as are securities and jewels from the bank’s vault. Gabriel Chestermarke and his nephew Joseph have unaccountably refused to call in the police to investigate the theft from their bank. When Betty Fosdyke shows up to visit her Uncle John, she finds it past belief that he would simply disappear – let alone that he would commit larceny. Unable to simply sit by and wait while a detective from Scotland Yard investigates, Betty elicits the help of the chief clerk at Chestermarke’s bank and launches into the middle of the mystery.