When treasury agent Steve Arthur learns that members of the international jewel-smuggling ring he has been investigating may be working at Sam Owen's carnival, he joins the carnival as a handyman. He soon begins to suspect Sam, Johnny the candy seller, and Pierre, who operates the carnival's wax museum, but has no evidence on which to arrest them. While searching for hidden gems, Steve becomes friendly with another employee, pretty Dolly Jordan. One day, Dolly gives Steve some candy that she made, and he finds a gem hidden in one of the pieces, causing him to suspect her as well. Later, while exploring the wax museum, Steve discovers jewels hidden in the eyes of some of the figures. Sam confronts Steve with a gun, and after a struggle, Sam escapes. Steve pursues him to the roller coaster, and the two men fight in one of the moving cars until Sam loses his balance and falls to his death. Steve's fellow agents, Dave and Miller, arrest Johnny, and Pierre is killed. With Dolly's innocence established, she and Steve happily resume their relationship.