A string of valuable pearls provides the motivation for the murder of Wareing, a widowed banker, who intended them for his daughter, Mary. She is comforted by Barton, a criminologist and friend of her late father, who appears to have left his financial affairs in a terrible state. Meanwhile, Mary's fiancé works diligently to identify the murderer. Although the criminologist places the blame on Wareing's butler, a reformed burglar, the killer is finally revealed to be Barton himself.