Thought I'd add some notes on the differences between this movie and the original novel. Of course, it can still be a good film even if it deviates from the novel!
We see the initial action at Fort Zinderneuf from the viewpoint of the relieving force. The story about Beaujolais and Lawrence meeting on their way back to Europe is cut; Lawrence has been merged with Beaujolais, making him Lady Patricia's patient suitor.
The Geste brothers for most of the movie are considerably older than in the novel. In the book, John Geste and Isobel are 19; I believe this makes Beau and Digby (twins) 20. The problem with 'older' brothers is that it implies they've been living off Lady Patricia well into adulthood! The actor playing Beau is about age 37, the actor playing Digby is 27, the actor playing John Geste is 22, actress playing Isobel is 20.
Claudia and Ghastly Gussie are cut.
A secret revealed at the end of the novel is revealed early in the film, lessening the mystery of the jewel theft.
The intervening story of John Geste's travels to France, enlistment in the Foreign Legion, and training in North Africa are greatly abbreviated.
The Americans, Buddy and Hank, have reduced but important roles and also act as comedy relief. Most of their racial language has been removed, but they do congratulate someone on acting 'white'.
Boldini has been merged with the barracks thief (another Italian, if I recall correctly). A scene has been added to show LeJaune's sadistic streak when deserters are caught.
The novel's adventures after Fort Zinderneuf have been greatly condensed. Digby's death is rewritten.
