Ali Baba, son of the Kalif of Bagdad is brought up by the 40 Thieves after his father is killed by the soldiers of Hugalu Khan, who received the necessary information by traitor Cassim. Ali becomes the leader of the thieves and they are fighting for the freedom of his land. Per chance Ali captures the fiancee of Hugalu Khan, who turns out to be his girl friend Amara. After a few misunderstandings Ali uses her wedding day with Hugalu Khan as the day for the liberation of Bagdad.

St. Louis 1903. The well-off Smith family has four beautiful daughters, including Esther and little Tootie. 17-year old Esther has fallen in love with the boy next door who has just moved in, John. He however, barely notices her at first. The family is shocked when Mr. Smith reveals that he has been transfered to a nice position in New York, which means that the family has to leave St. Louis and the St. Louis Fair.

Although they are only janitors at a detective agency, the boys pass themselves off as sleuths and are engaged to guard an inventor delivering a new bomb. They outwit enemy agents after the bomb and wind up sinking a Japanese submarine.