With supplies of liver oil cut off from overseas during wartime, research was undertaken to find a local product as a source of vitamin concentrates. A valuable source of oil, often richer in vitamins than that previously obtained from overseas, was found in the livers of snapper shark caught in waters south of Victoria. The film illustrates the work of the Bass Strait fishing fleet and shows how the liver oil is processed at a Melbourne factory to produce the active ingredient used in a series of vitamin-rich products.