Brandon Edwards, a gem collector, acquires the largest star sapphire in the world, the "Eye of the Daughter of the Moon," which was stolen from China. While displaying the precious gem at a party, Edwards tells Mr. Wong that his life is in danger. During a game of charades, Edwards is killed and the gem disappears. The Chinese detective, Mr. Wong, later discovers that the jewel is in possession of the maid, Drina, who plans to return it to its original location. But Drina is also killed. After another murder, Wong exposes his old friend Professor Janney as the killer. He turns him over to Capt. Street and returns the "Eye of the Daughter of the Moon" to China.