Espionage:Never Turn Your Back on a Friend (Michael Powell, 1964 torrent

This was posted by TheExecutive, but the torrent refuses to complete - I hope this will be more successful.

This is probably the best of the 3 Powell "Espionage" episodes. It opens with a schoolmarm giving grammar lessons, and then... oh, never mind, just watch it. The suspense definitely holds you. In some ways, it resembles Lifeboat or Lord of the Flies.