The second installment in the Mr. Wong series concerns a precious gem that is stolen in China and turns up in the hands of dubious American jewel collector Brandon Edwards (Morgan Wallace). The Eye of The Daughter of the Moon is said to be the largest sapphire in the world but presently it also seems to bring a fatal end to all who come into it's possession, including Edwards and those around him. Leave it to the clever Detective Wong (Boris Karloff) and his manservant Willy (Lee Tong Foo) to get to the bottom of things!