Dutch shipbuilder continues to build submarines for the Nazis while secretly working to sabotage their war efforts.

Efficient propaganda from the Archers production team that nicely ties in Richardson's well-played hero with the real-life Dutch maritime hero Piet Hein. The only real let-down, other than a few poor supporting performances, are some rather silly plot contrivances. For example, if the Dutch were actually able to successfully steal a German U-boat and sail it to England, I doubt the British would loudly trumpet that fact on the BBC Home Service, thus endangering the resistance effort in Holland, as well as the lives of their family members.

Not one of the Archers' most polished works, being a bit too unsubtle in its message and too cartoonish in its portrayal of the enemy. That is a fault of all films of this type, though; the main fault is a sudden veer into improbable melodrama in the final reel. It still remains a watchable film, even long after it had served its purpose.

Note: Both U-boats in the film, U 107 & U 108, was portrayed by the Dutch submarine O 15, which was used for this purpose at Dundee, Scotland for a few days in October 1942 before departing to patrol off Norway. The German crews were portrayed by the Dutch officers and men of O 15, which accounts for the somewhat amateurish acting in these scenes.