The Royal Mounties are called in when one of the armored cars owned by Maxwell, containing a gold shipment, disappears with driver George Hill suspected of trying to get away with the gold. Actually, Maxwell and two henchmen had poured acid on the brake lines, causing the car to crash. Genevieve, daughter of the Mountie chief, suspects Maxwell and Thomas Hatch, president of the bank shipping the gold, but she quickly becomes more trouble than help to Sergeant Renfrew in charge of the investigation. Renfrew and Constable Kelly drive the next shipment but Maxwell plans to make them crash the same way as Hill did. Renfrew steers the vehicle into a hillside and this gives him an idea of what happened to the other car. Diving into the nearby lake, Renfrew and Kelly discover the missing car and Hill's body, and also finds the gold shipment is a fake. When Renfrew goes to arrest Maxwell and his cronies, they all escape in an armored car. The air brakes fail and the whole gang meets the same fate as the murdered driver.