Sabrina Fairchild is the young daughter of the Larrabee family’s chauffeur, Thomas, and has been in love with David Larrabee all her life. David is a three-times-married playboy who has never paid attention to Sabrina because to him she was still a child. Eavesdropping on a party at the Larrabee mansion, as she has often done before, Sabrina notices David enticing yet another woman. Distraught, she leaves her father a suicide note and starts every car in the garage so as to kill herself. Instead she is interrupted by David’s older brother Linus, who escorts her back to her quarters above the garage.
Sabrina had been on the point of sailing for France, where she is to attend Le Cordon Bleu, the leading culinary school in Paris. After two years there, she returns home as an attractive and sophisticated woman. When her father is delayed from picking her up at the station, David offers her a lift instead without even knowing it is Sabrina.
Once David realizes who she is, he is quickly drawn to Sabrina and invites her to join him at a party at the mansion. When Linus sees this, he fears that David’s imminent marriage to Elizabeth Tyson may be endangered. If the engagement is broken, it would ruin a profitable opportunity for a great corporate merger between Larrabee Industries and Elizabeth’s very wealthy father’s business. Instead of confronting David about his irresponsibility, Linus pretends to sympathise with him and in a moment of inattention David sits down on champagne glasses he has placed in his pockets, so that he is incapacitated for a few days.
Linus now takes David’s place with Sabrina on the pretext that “it’s all in the family” until both fall in love, although neither will admit it. In fact Linus’ plan is to pretend to be accompanying Sabrina back to Paris but not to join her on the liner. However, when he reveals his intention to Sabrina instead, she agrees to leave the next day and never come back.
The following morning, Linus has second thoughts and decides to send David to Paris with Sabrina. This means calling off David’s wedding with Elizabeth and the big Tyson deal, and he schedules a meeting of the Larrabee board to announce this. However, David enters the room at the last minute and declares that he has decided to marry Elizabeth after all. David helps Linus recognize his own feelings for Sabrina and assists him in rushing off to join Sabrina’s ship before it leaves the harbor. Linus and Sabrina meet on board and sail away together.