Nils Ahlen (John McCallum), a Swedish scientist, discovers a sensational method to transform the impulse of sound into electrical power. The industrial and war potential of his discovery is enormous. His wife Helga (Mary Laura Wood) disappears with his young assistant, Sven Nystrom (Anthony Dawson) and secret parts of his invention are stolen. The Police Inspector (Jack Warner) and his force soon discover the escape route taken by the fugitives - towards the Northern frontiers. Leaving the roads and marks of man-made civilisation, both parties take to the desolate, bitter and trackless wastes where Lapp tribes and their reindeer herds eek out a precarious living. Eventually the forces of the sub-arctic tell in favours of the hunters who, in a breathtaking climax, gain their quarry.