In a Trieste gambling casino, the cynical Count Armalia tells his friend Rudi Pal that the only thing separating aristocrats from peasants is luck. Later, in a waterfront cafe, he decides to prove his point by offering the club's singer, Anni Pavlovitch, money and a wardrobe to stay at an upper class resort hotel in the Alps for two weeks and pose as his friend Anne Vivaldi, an aristocrat's daughter. When Anni first arrives, she meets Giulio, a philosophical postal clerk who has no desire for wealth. She also meets her old friend Maria, who is happy being a maid in the hotel and warns Anni not to become the victim of Armalia's joke on his friends. That evening, Anni attracts the attention of Rudi, who is dining with his fiancée, Maddalena Monti, her father, Admiral Monti, and Contessa di Meina. Rudi begins to falls in love with Anni, but she is more attracted to Giulio, even though she accuses him of impertinence when he tells her his feelings. Hoping to lure Rudi into proposing to her, Anni extends her stay beyond the two weeks while the Contessa, who has been suspicious of her from the beginning, wires Armalia for information on her. When the reply comes through the post office, Giulio reads it and learns the truth, but on the way to deliver it, he meets Anni, who goes to his cottage and realizes that she loves him, even though she still thinks that marriage to Rudi will bring her greater security. Later, she falls and Giulio loses the telegram going to help her. On the evening of an annual costume party at which the hotel guests dress as peasants, Anni snubs Giulio when he offers her flowers, but later confesses her love. She still plans to marry Rudi, though, whom she has finally gotten to propose, after refusing to be his mistress. The next day, Rudi tells Maddalena that he is in love with Anni and she steps aside, then suggests that they dine together that evening. While Maria helps Anni pack, she tells her that she no longer has a heart and that the gaudy red beaded dress she plans to wear is what she is really like. During dinner, Giulio delivers a copy of the telegram to the Contessa, who shows it to Rudi and the others. Maddalena is genuinely sympathetic, and Anni tells Rudi that he should marry his childhood sweetheart because she really is a lady. Finally, after being comforted by Maria, Anni realizes that Rudi did the right thing and she leaves the hotel after the manager demands payment of her bill. When she leaves, taking only her peasant costume from the ball, Giulio is happily waiting for her.