This film is captivating on a number levels. The basic story is set against the backdrop of the wreckage of post-war Berlin; by now split-asunder by the border between East and West and the Soviet occupation. The first scene sees a Briton, innocent and young Claire Bloom, flying into a foggy Templehof Airport to be greeted by her new German sister-in-law whom she has never met. The pair are observed by a small boy whose role in the film is a sort of liaison character - a messenger boy and spy for Mason. Hildegarde Knef, an extraordinarily attractive and complex blonde, plays the role of the sister-in-law and it is plain from the tension between the women that there is more than just post-war angst in the air. While it is very clear that she and her husband, a British officer and Doctor, are very much in love, it is plain that she is in a state of great anxiety for some inexplicable reason. When the character played by Mason keeps appearing, the unease of Knef seems to become more acute. It soon becomes clear that he is living a twilight existence working with black marketeers and at odds with the aggressive underworld boss for whom he is working. Bloom is fascinated by him and to Knef's inexplicable, even jealous annoyance, accepts dates with him. There is an interesting exchange between the women where Knef comes out with words that you feel are not entirely just dialogue between to characters "there's not so much difference in our ages, but there's a hundred years in the way we've lived" the words of a German woman who has lived through the fall of Berlin and all it's horrors, to an evidently sheltered young British woman. Ultimately it emerges that Mason is the presumed-dead husband of Knef who turned up after she'd remarried; meaning her marriage to her British husband is null and she ultimately has to admit this to him, though he is predictably loving and kind about their predicament.
Inevitably, Bloom falls deeply in love with Mason, and when she gets kidnapped and trapped in the East by Mason's boss, a creepy individual who spies on them, Mason rescues her. Their attempt to escape him and cross the border to the West fails and they are forced to run through ruins and debauched buildings where people are living grim lives of new-poverty. Chased by police, they escape into a building where a prostitute allows them to spend the night in her flat - being paid to get out. Predictably Bloom seduces Mason, but you sense that they are doomed. In the morning they are collected to be smuggled across the border by a friend of the family; who brings a van into the heavily snowy street to drive them across the border and a new life of hope. On the way Mason is killed.
The story itself is interesting, but the acting, particularly by Mason and Knef is outstanding. The haunting world of post-war Berlin makes this a period piece in itself just for the vision of the peacetime wreckage - and the implications it had for the future of the city. There are a few films of this kind - the other one that comes to mind is Roberto Rosselini's "Germany Annee Zero" - another haunting vision of ravaged, post-war Berlin.