After Mary Allen drops a blood-stained knife, Judge Robert Craigin's dead body lies next to her. Mary secures a secretarial position with Judge Bruce Craigin, the dead man's younger brother. Professor Galt, a criminal psychologist, and Detective Hooker believe that Mary committed the crime. Craigin and Mary fall in love and are married. Galt persuades Craigin to let Mary furnish their new home because a clue to the solving of the murder is the artistic furnishings of the room in which the murder victim was found. The similarity between the decor of the house and the crime room convinces Craigin that Mary murdered his brother, but Thomas Gray confesses to the crime. He had been in the room waiting to avenge his wife's wrongs on Craigin. When Craigin attacked Mary, she lifted her paper-knife and fainted, and Gray killed Craigin, leaving the murder weapon in Mary's hand. Mary and Bruce find happiness together.
