The highlight of this movie set on a German cargo ship during the Second World War are the superb performances offered by Marlon Brando and Yul Brynner. Brando plays a German expatriate (disguised as a Swiss national) who's living in British ruled India in 1942. He ends up being drafted (very much against his will) by the British to go undercover as SS agent Keil to divert the cargo ship (which is carrying a very valuable - to both sides - cargo of rubber) into American hands. Brynner plays Mueller - the ship's captain - a man with a drinking problem trying to regain his reputation after having a ship torpedoed out from under him while he was drunk, but a man who's also no fanatical Nazi.
Both are very believable in their roles. There's also a strong performance from Martin Benrath as First Officer Kruse - who is a fanatical Nazi, who doesn't trust his captain, and who's as happy to have an SS officer on board as the captain is unhappy about it.
The movie is always interesting. It's not an action movie in the modern sense of the word, but it's increasingly tense as suspicion grows about Keil, and as the ship awaits a report from Berlin about him. As good as Brando and Brynner and even Benrath are, though - and as tense as the movie becomes about whether Keil's real identity will be uncovered - the most powerful part of the movie might have come in a scene featuring Janet Margolin. She played a Jewish medical worker who was taken prisoner along with a number of American sailors when their ship is sunk by a U- boat. Speaking with Keil as he tries to convince her that he's on her side, his SS identity notwithstanding, she recounts - in surprisingly and uncomfortably (even for today, and so shockingly so in 1965) graphic detail - her abuse at the hands of the Gestapo. Without going into detail, the words "hour after hour after hour" are haunting. It was a truly sobering scene. You can't watch it and not find yourself in sympathy with a character who otherwise really isn't that central to the overall story.
This is, overall, a very good movie with a very strong cast. (8/10)