Warren William is Michael Lanyard, the Lone Wolf in his sixth appearance in the role. He's been called in to help out the authorities safeguard a trove of pricey jewelry aboard a ship in the harbor, and comments on the simplicity with which he could steal them if he were still in the business. Soon he is approached by a bunch who want to steal them, but switches roles with manservant Eric Blore.
William is playing with the fumes of time as King Rotter of the Pre-Codes, although he is now a reformed character. Edward Dmytryk directs this in a rather off-handed manner, probably because he had five other movies to helm that year. There's fun supplied by a supporting cast that includes Ruth Ford, Victor Jory, Thurston Hall, Fred Kelsey, and Victor Kilian, but the net effect is slight.