Lina McLaidlaw (Joan Fontaine), the shy and unexperienced daughter of wealthy General McLaidlaw (Cedric Hardwicke) falls in love with Johnnie Aysgarth (Cary Grant), a charming if not too trustworthy playboy. Contrary to the paternal opinion Lina decides to marry Johnnie and they elope for the Continent where they spend their honeymoon. After they are back and settled in their rented beautiful new home, Lina discovers that Johnnie is broke and he was hopelessly counting on her small allowance to support them both. Because of Lina insistence he accepts a job offer from his cousin, Captain George Melbeck (Leo G. Carroll), but it seems clear that Johnnie is more apt to borrow money than to work for it. One day an old friend of Johnnie, 'Beaky' Thwaite (Nigel Bruce) drops for a visit and from his careless chatting Lina realizes that Johnnie is a gambler and a liar. After other misfortunes Jonnhie develops new interests, in poisons for instance, and in a new money making scheme with Beaky as a partner. Lina is torn between her irrational love for Johnnie and the suspicion he can be far more dangerous than she has ever feared.