In the heart of the blossoming Mackenzie district, commercial fishermen are drawing rich harvests of the whitefish and lake trout from the chilly depths of Great Slave Lake, the commercial possibilities of which were explored by Government scientists in 1944. The film takes a look at this northern enterprise, showing operations of independent fishing companies as they catch, process and ship huge quantities of fish to the markets of the world. Concluding sequences show the versatility of the snowmobile during the winter fishing season.