 A rash of murders (by an unknown "monster") is plaguing London, and police are baffled.A newspaper reporter, Bruce Adams (Craig Stevens), finds one of the murder victims while coming home from a bar at night and calls the police.The next day, two American policemen, Slim (Bud Abbott) and Tubby (Lou Costello), who are working for the London Police Force, respond to a mob fight at a Women's Suffrage Rally in Hyde Park.