First of all, a five-year-old girl named Agatha has gotten accidentally locked in a new burglar-proof bank vault and she is hysterical. She will die of suffocation unless she can be rescued quickly. Jimmy Valentine happens to have his suitcase full of specialized safecracking tools with him--but if he opens the suitcase his fiancee Annabel and her whole assembled family will realize that he is not a legitimate small-town businessman named Ralph Spencer but a professional criminal! This revelation, of course, will be validated if he uses the tools to save the terrified child. But he is the only person who can open the vault because of its time lock, and if he doesn't free little Agatha she will die. Jimmy's fiancee is pleading with him to do something.
Annabel turned to Jimmy, her large eyes full of anguish, but not yet despairing. To a woman nothing seems quite impossible to the powers of the man she worships.
“Can't you do something, Ralph—try, won't you?”
In the meantime, Jimmy's nemesis Ben Price has come to the bank in Elmore to arrest him for the three bank jobs he pulled in Indiana right after being released from prison at the beginning of the story. Jimmy's past has come back to haunt him. It looks like his reformation is completely voided one way or another. He is threatened with losing everything he has gained by reforming--most importantly his fiancee Annabel, who was responsible for his wanting to reform in the first place. But Jimmy knows he must do the right thing, which proves that he has become a completely new man.
He set his suit-case on the table, and opened it out flat. From that time on he seemed to be unconscious of the presence of any one else. He laid out the shining, queer implements swiftly and orderly, whistling softly to himself as he always did when at work. In a deep silence and immovable, the others watched him as if under a spell.
In a minute Jimmy's pet drill was biting smoothly into the steel door. In ten minutes—breaking his own burglarious record—he threw back the bolts and opened the door.
Ben Price has observed Jimmy's noble sacrifice and decides not to arrest him after all, but to let him retain his new identity as Ralph Spencer, small-town businessman and soon-to-be family man and pillar of the community. Jimmy will have a lot of explaining to do to Annabel and her whole family, but the reader feels confident that they will forgive him for the same reasons that Ben Price forgave him. Ironically, Jimmy's reformation has been "retrieved" by his doing the thing he has supposedly given up doing--that is, using his expertise and state-of-the-art professional equipment to break into a bank vault.