Fern Barrett is a girl of high principles, and such people are born to be tested. When she and her husband Terry are forced by circumstances to take employment servants in the household of powerful financier Quentin Dorey, a bachelor, her trials begin.

Terry becomes increasingly self-centred and feckless, while Fern finds herself more and more attracted by the charm and sympathy of her employer. She also incurs the hatred of Quentin's embittered mother, who has guessed something about the girl's background which Fern is desperate to conceal. What is Fern to do? Because of her, alas, a promise is forever.