 Meanwhile, acting on intelligence following the smashing of a spy ring in Montreal, Royal Canadian Mounted Police (RCMP) officers Don Roberts and Kay Conway go undercover in a settling party headed for the Yukon.Marlof also has agents, Beck and Reed, in the party en route to the site of the planned missile bases.Their attempts to disrupt the party only call the attention of the Mounties to the larger plot who, once the settlers finally reach their goal, continue to pursue the troublemakers, uncover their plot against the free world, unmask Marlof and bring them to justice.