The killing of Khan's friend, a physician, is linked to an international crime syndicate, dealing in gambling and narcotics which appears to be moving into California. 

Khan undergoes some pangs of conscience when a former British agent stands accused of diamond robbery and the evidence is overwhelming. The man saved once Khan's life.

Ohn Chang, an overwrought father hires Khan to find the man who murdered his daughter.  

Khan goes after a mysterious swordsman, wearing the mask of a secret Chinese society, who has murdered a wealthy San Francisco manufacturer and threatens the dead man's partners. The victim was accused of causing a fire that cost the lives of a number of Chinese workers.

A black football quarterback gets embroiled in a frame-up for the murder of his girldriend.