Dorothy Shaw and Lorelei Lee are singer and close friends, together they go on a sea cruise on the Queen Mary liner across the Atlantic on a tour to the French capital. Both girls are not married, they are in search of suitors. Dorothy prefers to marry for love, and Lorelei is only interested in money. Meanwhile, Lorelei is already engaged to the millionaire Gus Esmond. His suspicious father sends for his daughter-in-law a private detective, instructing him to monitor whether the girl is faithful to Gus, and wants to prove to her son that Lorelei loves him only for gifts.