Nayland Smith tries to prevent the arch-criminal Fu Manchu from acquiring the Mask and the Sword of Genghis Khan, items with which he would be capable of ruling the world.
I'd heard about this movie for years before I'd had a chance to see it, as my local Creature Feature never got around to any of MGM's horror movies. It's pretty nasty stuff for its time; I don't think I've ever seen Karloff as viciously evil as he is in this role, and the tortures he devises are quite cruel. It can be a bit of fun if you don't take it seriously, otherwise, the racism may leave a fairly bad taste in your mouth. It also features Myrna Loy as Karloff's daughter, and she's even more evil than he is.