A diamond is stolen at a houseboat party given by the district attorney. He gives the thief a chance to return it by putting an empty box on a table and turning out the lights. When the lights are turned back on the box is gone, and the district attorney has a knife in his back and is quite dead. The police and the coroner arrive. There are several attempts made on the life of the coroner. Ruth Whitman is found hiding in a grandfather-clock, holding the gem box. She claims the box was pushed into her hands and she was pushed into the clock. The district attorney's butler/valet tells the coroner he saw who killed his employer and a few minutes later he is also murdered. The mystery deepens.
Raymond Griffith
as Mr. Green
Edward Martindel
as Mr. White
Earle Williams
as Mr. Black
Tom McGuire
as Inspector Brown
Dorothy Sebastian
as Dorothy
Granville Redmond
as Grey – a Valet
Richard Arlen
as Reporter (uncredited)
Monte Collins Sr.
as Milkman "Juror" (uncredited)
Roscoe Karns
as Party Guest (uncredited)
Isabelle Keith
as Party Guest (uncredited)
Dick La Reno
as "Jury" Foreman (uncredited)
Carl M. Leviness
as Party Guest (uncredited)
