Private detective Donegal Dawn, is summoned by the police commissioner to solve the reasons for a crime wave in Chinatown, and scoffs at the official ruling on tong-killings. His friend, Robert Rand, has has fallen for Zenobia, a clerk at Chan Tow Ling;s curio shop. Dawn tells Robert that their live would be in peril if he tries to take Zenobia away from Chinatown. That night, Robert breaks into the shop's cellar where he hears strange music and voices, and sees a weird ceremony in which (the mesmerized) Zenobia officiates as a priestess. Robert is captured by the worshipers. Dawn tracks the sinister "Order of the Black Rober" but can not find a trace of Robert, Zenobia or the cultists.
