A young woman, disheveled and greatly distressed, stops criminologist Marcel Levington on the street and begs him to find a doctor for a man who is dying inside a nearby house of ill repute. Marcel and his friend, Dr. Rogers, enter the house and find the man, a prominent lawyer, dead, his heart pierced by a hatpin that the doctor recognizes as the one he recently gave his daughter Toinette. Rogers announces that the man has died of heart failure, returns home and demands an explanation from his daughter, who explains that she was lured into the house and attacked by the man. Realizing that Toinette killed the lawyer to defend her honor, Rogers and Marcel agree to protect her. Marcel retrieves Toinette's pocketbook from the proprietor of the house, Mrs. Clifton, who had planned to blackmail the girl, and then returns to Toinette, with whom he has fallen in love.