The essentials of the story are true, but the characters in the movie are fictional. As he did with
Shakespeare in Love, screenwriter/playwright Tom Stoppard brilliantly interweaves the real and the imaginary to illuminate not only his characters' era but our own. Stoppard is fascinated with puzzles, wordplay, secrets, and stories within stories, all of which lend themselves very well to the Bletchley code-breakers. The movie brilliantly depicts the desperate atmosphere and heart-breaking dedication of the people who knew that their success – or failure – could do more to determine the outcome of the war than a thousand soldiers with guns.
The performances are excellent, particularly Northern, whose character has had to sacrifice what he once thought of as honor to serve a greater cause, has had to betray in order to be loyal, and has had to keep too many secrets. Winslet's only failing is her entirely unsuccessful effort to look dowdy. But she and Scott are marvelous at showing us something we seldom see in movies, really smart people using their intelligence.