Mad scientist works on a death ray in his mountain hideaway.

After an extended stay in England, Sophie Lang returns to America. She is beautiful, sophisticated--and a notorious jewel thief. A New York police detective who's been trying to nail her finally comes up with what seems a foolproof scheme--to catch her off guard by having her fall for a handsome and suave jewel thief who happens to be in the U.S. traveling under an assumed name.

Rancher "Utah" Neyes crosses the border into Canada to meet his partner, only to find that the latter has been murdered by a gang led by "Nails" Nelson. "Utah", with the aid of RCMP Jack Craig and fur-trapper Ivy Jenkins, manages to clear his own name of suspicion and also break up Nelson's fur-stealing and smuggling racket.

Ships disappear on route across the Arctic Sea, and a special submarine is sent to investigate.