Chan is on his way back from completing the London case—they always mentioned the previous case—to go on "vacation" to Paris, but this is just a way to make people think that he is innocently there. He is on a case for some London bankers and customers who say that some bonds from the Lamartine Bank in Paris are forged, so they hired Chan to solve the case. After various murder attempts on Chan and other killings, including that of his assistant, Nardi, and the ex-boyfriend of Yvette, which was staged by a blind beggar named Xavier, a "crazed" World War I veteran who wants his money and wants it now!
The murderer was Xavier, but he is actually not real; he has alternately been played by both Corday and Latouche—Latouche appearing as Xavier when Corday was with Charlie, and Corday appearing as Xavier when Charlie meets Latouche at the Bank. Chan takes young Victor Descartes with him to find Xavier, and while they search Corday's and LaTouche's lair where they have been printing the counterfeit bonds, Latouche (as Xavier) arrives. Chan and Descartes kill the lights, and Latouche shoots at Chan's flashlight, apparently hitting him. But Chan has mounted it on a broomstick to decoy Latouche, and Descartes is able to capture Xavier/Latouche. Then the police arrive (summoned by Chan's son Lee), giving Chan a chance to explain how Corday and LaTouche created alibis for each other by alternately playing Xavier.