Caroline Actually, it was made into three feature movies, one BBC made-for-television movie, a British theatre one , and several radio adaptations, including one with Orson Welles. None stick to the book, and nearly all include a love interest for Hannay, which is not in the book, either.
Sharon Two movies, actually. One by Hitchcock that only barely follows the same plotline, and one in 2008 that more closely follows the story. The changes in the '08 movie aren't terrible, and it's an enjoyable movie, but the book is more interesting.