A family of con artists saves the life of a wealthy old woman and plots to fleece her.

Bogus Colonel Anthony Carleton, known to his wife and children as "Sahib" because he pretends to have served in India, heads a clan of high class con artists working on the French Riviera. While he cheats at cards, Marmy, his wife, helps their children, Richard and George-Anne, promote profitable marriages. After Sahib wins a large amount of money from Richard's prospective future father-in-law, Jennings, the Monte Carlo police expose Sahib and the now destitute family is is forced to take the boat train to London using tickets provided by the police. Although George-Anne is in love with her suitor, Duncan Macrea, she will not marry him because he is not rich enough, even when he tells her that he does not care what her past has been. On the train, George-Anne meets Miss Ellen Fortune, a kind but lonely spinster who, in her old age, inherited a lot of money from a man who was once her fiance. Miss Ellen invites them into her first class compartment, buys them dinner, and then, after they care for her during a train wreck, she asks them to stay with her in London. Because they are desperate, they decide to stay and, to convince her suspicious lawyer, Felix Ansthruther, that they are not what they actually are, go to work. Richard becomes a mail clerk in an engineering firm and Sahib becomes a salesman for the Flying Wombat motor car. Soon Miss Ellen's sweet nature begins to change all of them. Richard and Sahib are successful at their jobs and George-Anne begins to feel guilty about their plan, certain that the others are still only after the money. When Miss Ellen collapses on her birthday and they learn that she has changed her will in their favor, they not only do not care about the money any longer, but offer to support her themselves when Mr. Anstruther says that her fortune has eroded to nothing. Finally changed, Richard marries Leslie Saunders, his boss, George-Anne marries Duncan, Sahib becomes the London sales manager for the Flying Wombat and Ellen comes to live with them in a country cottage.