Daniel Robin has become mixed up with a band of criminals known as "the 13," and is shot when he refuses to do their bidding. His daughter Ruth, brought home from boarding school, reaches his bedside before he expires. He tells her that she will be given thirteen keys. Instructions will be provided with each key and, if she follows the instructions, she will eventually fully learn of her birthright. Many adventures then follow as Ruth attempts to solve the puzzle of each key and establish her true birthright.