On vacation from her job in the civil service, Judith Farrow (Julie Andrews) heads to the Caribbean where she befriends a debonair Russian named Feodor Sverdlov (Omar Sharif). The two quickly fall in love, but Judith's feelings are tested when Sverdlov is revealed to be a Russian agent eager to win her over to his cause. Back at home, Judith is instructed never to see him again, but can't shake the attachment, and soon finds that both of their lives are in danger.