While watching from her train window, Nikki Collins witnesses a murder in a nearby building. When she alerts the police, they think she has read one too many mystery novels. She then enlists a popular mystery writer to help her solve the crime on her own, but her sleuthing attracts the attentions of suitors and killers.
Deanna Durbin
as Nikki Collins / Margo Martin
Ralph Bellamy
as Jonathan Waring
David Bruce
as Wayne Morgan
George Coulouris
as Mr. Saunders, Circus Club Manager
Allen Jenkins
as Danny (Waring chauffeur)
Dan Duryea
as Arnold Waring
Edward Everett Horton
as Mr. Haskell
Patricia Morison
as Joyce Willams, Morgan's Girl
Maria Palmer
as Margo Martin, Circus Club Singer
Elizabeth Patterson
as Aunt Charlotte Waring
Samuel S. Hinds
as Mr. Wiggam, Waring Lawyer
William Frawley
as Desk Sgt. Brennan
