- Philo Vance, dilettante detective
- John F. X. Markham, district attorney
- Sgt. Ernest Heath, Homicide Bureau
- Alvin Benson, wall street broker, dead in his home as story opens
- Major Anthony Benson, brother of the murdered man
- Mrs. Anna Platz, housekeeper for Alvin Benson
- Muriel St. Clair, a young singer
- Captain Philip Leacock, finace of Muriel St. Clair
- Leander Pfyfe, friend of Alvin Benson
- Mrs. Paula Bannon, friend of Leander Pfyfe
- Elsie Hoffman, secretary of the firm Benson and Benson
Locale: New York City
Synopsis: District Attorney John F. X. Markham invites Philo Vance along to a murder scene. Broker Alvin Benson has been found dead in his home. Sgt. Ernest Heath is in charge of the investigation. A drawing of the scene is provided:
Not much to go on for clues: a grey Cadillac was seen parked outside with fishing tackle sticking out the back, in the room are found a pair of ladie's gloves and a handbag, with the monogram "M. St.C". The housekeeper, Anna Platz, heard the shot in the night but did not recognize it as such.
The handbag turns out to belong to Muriel St. Clair, who had been to dinner with Benson, but denies any involvement. Muriel, however, is engaged to Capt. Philip Leacock, who was none too pleased to find that she has been stepping out with Alvin Benson.
Vance finds that five people had motive and opportunity to do away with Benson, and examines a theory for each to find the murderer.