The Canadians have discovered a valuable substance called Compound X, which can cure infantile paralysis. When a country at war with Canada learns that Compound X also contains magnetic properties that could aid them in their warfare against the British, they send agents to infiltrate Canada and steal a large quantity of the substance. It's up to Sgt. King (Allan Lane) and his Mounties to track down the agents and put an end to their scheme.

• Allan Lane
• Robert Strange
• Robert Kellard
• Lita Conway
• Herbert Rawlinson
• Harry Cording
• Bryant Washburn
• Budd Buster