Well made and well acted action film, let down by a plot that strains credibility, even for a propaganda piece. I doubt the Admiralty would be pleased with a captain who takes his command, without orders, a thousand miles away from his assigned operating area, and I further doubt any British submarine would have been able to proceed unnoticed into the Baltic in late 1942. Yes, propaganda, but it gets a tad too silly, with commando raids and the like, to put it among the classics of the genre.