A masked girl sits in a store window in New York writing cards to demonstrate a fountain pen Everybody is curious about her because she is so pretty and she becomes nicknamed the Angel in the Mask A certain boy from the country Bob Singleton chances to pass the window He is forlorn because he cannot get work The masked girl holds up a card on which is written a word of friendly encouragement At the boardinghouse where the boy is staying a robbery and murder are committed incriminating evidence is found in Singletons room and he is taken to prison