Based on the Laszlo Aladar play, a couple of thieves get together to rob a wealthy lady, but he falls in love with her.
In a Venice hotel Gaston Monescu (Herbert Marshall) plans a romantic evening with Lily (Miriam Hopkins). She pretends to know aristocrats. In a suite François Filiba (Edward Everett Horton) tells police he was robbed by a doctor. Lily tells Gaston he robbed the man, but he says she took the wallet from him. Gaston shakes it loose to get it back. The two thieves love each other.
Perfume owner Mariette Colet (Kay Francis) tells Adolf Giron (C. Aubrey Smith) she won't cut salaries. Mariette tells François and the Major (Charles Ruggles) she loves neither. At the opera with the Major, Colet loses her bag with diamonds. Lily advises Gaston to return the bag to Mariette for the reward. A Trotskyite lectures Mariette, and Gaston gives Mariette her bag, criticizing the Major's love letter and her make-up. Gaston watches Mariette open her safe and advises her to keep more cash there. She hires him as her secretary, and he takes control, increasing her burglary insurance. Gaston dictates to his secretary Lily. Mariette asks Lily to take over some of Gaston's work. Lily is jealous and wants to rob Mariette soon. Gaston and Mariette go out and say goodnight at 2 a.m.
At a party Adolf asks Mariette about Gaston, and she tells Gaston to go over the books with Adolf. Gaston quarrels with Adolf and gets rid of him. François asks Gaston if he was ever in Venice, but Gaston says no. Gaston orders train tickets to Berlin and sends roses to Mariette in his memory. Gaston plans the next day with Mariette and says good-bye. He insists she go out, but she asks him to kiss her. Now Gaston wants her to stay, but Mariette goes. Gaston calls Lily to postpone their trip. François recalls that Gaston was the doctor in Venice. Adolf insists on seeing Gaston and says he must leave; but Gaston says that Adolf is a crook too. Gaston finds Lily opening Mariette's safe, and Lily takes the cash. In Gaston's room Mariette takes off her jewelry and opens her safe. Gaston tells her that Adolf has been robbing her. Gaston says who he is and admits he took the money; but he is in love with her. Lily appears and says she took the money. Lily scolds Gaston and Mariette, then leaves with the money. Gaston says good-bye to Mariette so that she won't be visited by police. Gaston shows her the pearls he took for Lily. In the cab Lily has the pearls, and Gaston the money.
Director Lubitsch gives a certain style to this sophisticated comedy in which all the sex is merely implied; but I suspect the censors would not allow this movie to be shown later because the thieves get away with their crimes.