The Door That Has No Key is a novel written by Cosmo Hamilton and published in 1913. The story revolves around the protagonist, Hugh, who is a successful playwright and a wealthy bachelor. He lives a luxurious life and has everything one could desire, but he feels that something is missing.One day, Hugh meets a mysterious woman named Cynthia, who intrigues him with her enigmatic personality. He falls in love with her, but she disappears without a...