This routine espionage drama is based on a novel by Graham Greene about a low-level British informant who is caught in a trap. Castle (Nicol Williamson) has a desk job in British intelligence. Around him are heavyweights like Col. Daintry (Richard Attenborough), Sir John Hargreaves (Richard Vernon), and Percival (Robert Morley) who will cold-bloodedly stop at nothing to do their jobs as they see fit. And Castle certainly is a nobody compared to them. One day when a friend of his in Africa needs some help, Castle is conned into supplying the Eastern block countries with info on demand. No one suspects him because of his low position, but when his office partner is hauled off, Castle begins to rethink his situation. This was director Otto Preminger's last film.
~ Eleanor Mannikka, All Movie Guide