His Duty (1909)

It's Bob Allen's twenty-first birthday. His mother and his brother Jack, a policeman present him with a cap, personalized with his initals in the lining. Jack then goes to work and Bob goes out also. Later in the evening, Jack is called to the scene of a robbery, where he finds the cap with his brother's initials. Dismayed by the idea that his brother is a thief, he goes home and confronts Bob with the evidence. Though it breaks their mother's heart, Jack does his duty and leads his brother out in handcuffs.