In the 1890's, Suzie, an 18-year-old Chinese stowaway, leaves her hiding place on a ship after it docks in San Francisco, only to find herself in the middle of the tong wars and a witness to the murder of a runaway "love-slave." She makes her escape and finds work at the Mandarin Club, owned by her distant uncle Wong, who heads the Red Dragon tong.

A scientist develops a formula which will cause animals to regress to the form of their primitive ancestors, and tries it on himself with disastrous results.