This film covers the latter years of Canada's naval contribution to World War II. In particular, this film focuses on the troubles of the atlantic transportation route that was one of the most hazardous in the war. Of that route, no part was more dangerous than the region that naval command refused to have patrolled by long range aircraft, nicknamed the Black Pit. Thanks to this act of incompetence, Canadian naval forces were besieged by U-Boats while in this large area of the Atlantic until events force a needed change.