Mary Brammal, a female crook, is discharged from prison. Soon after, when she is at the end of her resources and starving in New York, she encounters Frances Van Brunt, the six-year-old daughter of cashier Van Brunt, of the First National Bank. Mary is being roughly moved on by a policeman, when Frances interferes and then gives poor Mary some money. Later Mary meets some of her old pals, and as they are forming to plan to rob a bank, they induce Mary to take part and go back to her former life. She disguises herself as a boy and secures a position in a bank as a messenger. The bank is installing a new vault, equipped with a new time lock, and Mary listens while the workman is explaining to Van Brunt and Harding, the president of the bank. When their backs are turned, she moves the time lock so that it will open the vault at ten that night, as well as ten the next morning, and then conceals herself beneath a counter. The vault opens and Mary removes the currency to a suitcase. She then closes the vault and leaves by a window. The next morning the vault is found to be empty when it is opened, and it is then discovered that the time lock has been set twice. The president suspects Van Brunt, and that evening goes with a detective to Van Brunt’s home and arrests him. Frances is grief stricken at her father being taken away, and follows the men to the street, crying bitterly. Mary is passing at the time, recognizes Frances, and inquires the cause of the trouble. Frances explains. Mary stops the arrest, explaining that she has the money in the suitcase, and that she is the thief. The party hear the whole story and Van Brunt prevails upon Harding to forego prosecution. Mary then seeks refuge in a convent.