Must-See Cinema! The mother of all conspiracy thrillers!
Korean War veteran Major Marco (Frank Sinatra) is troubled by a recurring nightmare in which Congressional Medal of Honor hero Raymond Shaw (Laurence Harvey) carries out Communist instructions to shoot fellow American POWs. Working for Intelligence, Marco unravels a cunning Red plot to brainwash his old platoon and to turn Shaw into an assassin. Shaw’s father-in-law is the ranting McCarthyite Senator Iselin (James Gregory), a mouthpiece for Shaw’s ambitious mother (Angela Lansbury), a political background which gives the killer access to the highest in the land. Who is Shaw’s American control, when and where are they going to aim him? 
Director Frankenheimer’s version of Richard Condon’s tragically prophetic novel looks even better now than it did then. Its greatest virtue lies in its brilliant balancing acts: political satire and nail-biting thriller, the twin lunacies of the Right and Left, and the outrageously funny dialogue during the parallel courtships set against the sadness of the unloveable Shaw’s predicament. Among a marvellous cast – star-wattage Sinatra, hilariously dumb Gregory, the giggling Peking Institute brainwasher played by Khigh Dhiegh – Lansbury stands out. An Iron Lady to savour, for a change. A masterpiece.
– Brian Case, Time Out Film Guide