Slaves in San Francisco: this is the fate of the poor Chinese girls who, snatched from their native villages, are handed over to the highest bidders on the other side of the ocean. Whoever investigates this dirty trafficking risks ending up strangled with a noose of black silk! The alluring Ah-Toy – better known as the Daughter of the Dragon – is at the head of the tong with her two shady accomplices: the sinister advisor Lao Tan, called the Black Claw, and the slippery gambler Wong Ha Gum. But, with Tex in town, things start to take a turn for the worse for the Chinese criminals: the first attempt to send the four pards to the cemetery fails, and then Wong watches on as his Gaming hall is destroyed.