Geoffrey, a young and impoverished writer, is desperately in love with Mavis, who lives at his boardinghouse and is also pursuing a writing career. Unable to marry her because of his poverty, in his anger he curses God for abandoning him. Soon Geoffrey meets Prince Lucio de Rimanez, a wealthy, urbane gentleman who informs Geoffrey that he has inherited a fortune, but that he must place himself in the Prince's hands in order to enjoy the fruits of his inheritance. What Geoffrey doesn't know is that Prince Lucio is actually Satan, who is using Geoffrey as an experiment to show God that he can corrupt anybody.