The well-known merchant Kasim Baba (brother of Ali Baba) is preparing to give a lavish banquet for the wealthy Chu Chin Chow, who is on his way from China. Abu Hassan wishes to add to his riches the property of Kasim and has installed the slave girl Zahrat in Kasim's house as a spy. Zahrat sends a message to Abu Hasan, lettin him know about the banquet. Hasan arrives at Kasim's palace in disguise as Chu Chin Chow. His gang of thieves rob and slaughter Chu Chin Chow while he is still traveling. Meanwhile, Kasim's brother Ali Baba discovers Hasan's secret cave and helps himself to some of the thieves' treasure. While Hasan impersonates Chu Chin Chow at Kasim's court, Kasim persuades his brother to tell him where his sudden wealth came from. Even as the greedy Kasim slips out to see what he can find at Hasan's cave, Hasan is plotting further violence and thievery. Zahrat gets her revenge on both Hassan and his forty thieves, lovers are united, and all ends happily.