On the contrary, Hitchcock did
replace what was on the page. He fired the original novelist (who had written a draft) and hired Samuel Taylor (who had co-written Vertigo
for the director) to write the movie instead. The change didn't help the film much, though, and the page doesn't save Hitchcock from at times clumsy direction. Witness the climax of the opening chase, where the girl seems to stumble into a biker like a moron, rather than out of desperation, confusion, or anything else that might look believable on screen. Witness the escape of Andre Devereaux from Cuba, secret documents in hand. Actually, don't -- Hitch chooses to play this moment off screen, rather than get any suspense out of it (despite spending considerable time setting up where the documents are supposedly hidden is his luggage, a scene that ends up wasting time showing off gadgetry rather than contributing to the whole -- no wonder the film was the longest the director ever made -- it has no discipline).