Sonya Rokoff acting as a representative of a European importing firm hires Victor Poten (Bela Lugosi), a Eurasian mad scientist who hates both whites and Asians, to ruin the tourist trade in San Francisco's Chinatown. Rokoff soon realizes that Poten has become an unstoppable monster, beyond her control. Poten's nefarious activities draw the attention of newspaper reporter Joan Whiting and her novelist boyfriend Martin Andrews who begin to investigate the mysterious, and violent events in Chinatown.