The story is told by the narrator (Falk) as he is reading a story to his sick grandson (Savage). It follows Buttercup (Wright) as she falls in love with poor farm boy Westley(Elwes), is wooed by Prince Humperdink (Sarandon), and kidnapped by Vizzini (Shawn) and his minions, Inigo Montoya and Fezzik (Patinkin and Roussimoff).
Westley has run off to seek his fortune, so that he can marry Buttercup but has been lost at sea after a pirate attack. Buttercup gives up her wait for Wesley after 5 years and accepts Prince Humperdink's marriage proposal. When she is kidnapped by rivals, she is then kidnapped from the kidnappers by the Dread Pirate Roberts (who was responsible for the death of Westley). The entire movie runs like this, with twist after twist. My favorite part was seeing Billy Crystal briefly as Miracle Max. He did an incredible job with such a small part. When they reach The Cliffs of Insanity in the film, some of you may recognize Cliffs of Moher in Ireland. It is beautiful!
The film pretty much stayed true to the book, written by William Goldman and published in 1973. The biggest difference I found was the narration is different. In the novel, Goldman claims his story is based on a previous version that was a satire of European royalty. In reality, the novel is 100% Goldman's story. The "based on" part was a literary device, which he started in the introduction and continued into the commentary throughout the story. He even went as far as to write a second novel, The Silent Gondoliers, under the name of this fictional "original" writer.
Later print editions of The Princess Bride included an epilogue that referenced Buttercup's baby. It included a kidnapping of the baby, Fezzik sacrificing his life to save the child, and Inigo's training as a swordsman. The 30th edition promised to have a sequel title Buttercup's Baby ready by the 35th edition, but that came out in 2009 without Buttercup's Baby. Goldman has admitted that he has not written the anticipated sequel.
If you haven't watched the movie, watch it as soon as you can. It is very good. There is girl stuff and guy stuff so it should be pleasant for all who watch. I watched it as a kid, so I'd go as far as to say it is okay for children too!