1941. When a German U-boat is sunk in Hudson Bay off the coast of Canada, six members of the crew are stranded on land. Coming upon a remote outpost, the Nazis kill the eskimo chef and take the other two inhabitants, Johnny and Mac, captive. Johnny manages to alert help by radio, but is shot and critically injured. Responding to the alert call, a plane is sent to their aide, but the Nazis overpower the crew, losing one man in the process.

The five remaining Germans escape in the plane, but when they run out of fuel they are forced into a crash landing, killing the pilot. Wandering, the survivors come across a religious settlement, comprised mostly of ex-national Germans, where they claim to be itinerant labourers and are offered hospitality. The Nazi leader, Lt. Hirth, believes he can convert these German settlers to Nazism, but his speech draws a bitter response from the community leader, Peter, who has already identified them from reports of their escape from Hudson Bay. Vogel, a reluctant Nazi, is invited to stay, but his intention is discovered by the others, and he is summarily executed for treachery.

Now reduced to three, the Nazis resolve to head for Vancouver, where they plan to meet a Japanese ship. They steal a car, then board a train headed west, but when the train stops for an Indian pageant, one of them is identified and captured, while the other two, Hirth and Lohrmann, are forced to flee on foot. Trecking across the wilderness, they encounter an English explorer, Philip Armstrong Scott, who infuriates them by comparing them to the Blackfoot Indians he is researching. When Scott's crew turn in for the night, Hirth and Lohrmann imprison Scott and make their escape with his guns but, with Scott and his men in pursuit, Lohrmann rebels against his commanding officer, knocking him out and fleeing alone. However he is cornered in a cave and Scott, despite receiving a gunshot wound, succeeds in overpowering him.

Recovering, Hirth continues alone, eventually stowing away on a goods train heading for the US border. There he meets Brock, a Canadian soldier gone AWOL. Subduing Brock, Hirth anticipates arriving on US soil where he can take advantage of American neutrality and demand deliverance to a German embassy. But when the train is stopped and inspected by US customs officers, Brock convinces the officers to treat the two stowaways as unitemised freight and send them back to Canada. With the train returning to Hirth's inevitable capture in Canada, the triumphant Brock strikes him down.