When actress Diana Baring is found in a daze beside her colleague’s murdered body, all evidence points to her guilt. During the trial, juror Sir John Menier doubts the verdict, but yields to pressure. Haunted by remorse, he launches his own investigation.
A film projectionist longs to be a detective, and puts his meagre skills to work when he is framed by a rival for stealing his girlfriend's father's pocketwatch.