The 39 Steps

In 1935 Alfred Hitchcock took the Scot John Buchan's adventure story The Thirty-Nine Steps, fixed a good number of Buchan's plot-holes, added a few of his own, and produced what is largely considered one of the best British films and best book-to-film adaptations of all time. I'm not sure it quite deserves those accolades, but it had some pretty inventive and innovative story elements. Also, an autogyro.

It's certainly the best film I've seen that features an autogyro (sorry The Rocketeer, not sorry The Road Warrior).

Anyway, despite one of the stupidest resolutions in film history -- but still not as stupid as the novel's titular "steps" being an actual staircase -- The 39 Steps still manages to be a suspenseful and exciting film. Though it's not often that Hitchcock failed to make a film that was exciting or suspenseful.