Everyone remembers the cold war, but how many people remember that it started in Canada? Russia and the west were lovey-dovey until a humble cipher clerk at the Soviet embassy in Ottawa defected and spilled the beans. Igor Gouzenko was his name, and his revelations set off a firestorm. Nobody wanted to believe him at first - they were weary from fighting Hitler, a new round of conflict was too much to handle.

Even if the politics seem dreary, this is a first-rate thriller, very much on the level of Hitchcock - it will keep you on the edge of your seats. There were so many bad red-scare movies, we forget there were also some excellent ones.