Jack Hawkins may not have been known for nuanced acting, yet he delivers a restrained performance in this believable film based on AP Scotland's true story. He plays a German officer who climbs through the ranks to a high-level position within the Nazi military, all while secretly providing information to the British over nearly three decades. The filmmaking creates a feeling of suspense and holds it effectively, particularly as the movie progresses. It’s something you don’t often see these days, but it's certainly enjoyable.

Source on TMDB