Dr. Paul Carruthers is frustrated because he thinks his employers, Mary Heath and Henry Morton, have cheated him out of the company's profits. He decides to get revenge by altering bats to grow twice their normal size and training them to attack when they smell a perfume of his own making. He mixes the perfume into a lotion, which he offers as a gift to Mary and Henry. When they turn up dead, a newspaper reporter decides to investigate.
Professor Morlant, a British Egyptologist, seeks immortality through the power of a jewel buried in the tomb of an Oriental idol. Upon his death, Morlant returns to earth to seek vengeance upon those who removed the jewel from his grave.
George Fowler arrives at the Mias saloon, and the proprietor, "Blak Jack" Hovey, orders a saloon girl, known only as "The Flame," to fleece him, but he has no money...
When a police officer is murdered, Captain Street looks to Mr. Wong to catch the killer. Prime Suspect: Frank Belden Jr., whose father is a businessman well known for both his success and dishonesty. Mr. Wong faces increasing danger and is nearly executed himself as the investigation develops in treachery and complexity. As Mr. Wong follows the trail of dead bodies, he uncovers a jewel smuggling ring on the San Francisco waterfront and a case much larger than the death of a police officer.