Every now and then while watching a movie -- when someone's hands are being sawed off ("Watchmen") or eyelids sliced away ("The Haunting in Connecticut") -- I turn my head sharply to the left. My creaky neck doesn't swivel as quickly to the right.

Josh Bazell is the first author who made me do that while reading a novel. It happened a few pages from the end, and while I highly recommend "Beat the Reaper," I will spare you the bloody, brutal, inventive details.

The screen rights to the mob-medical thriller were bought even before publication, and Leonardo DiCaprio will produce and may star. If "Beat the Reaper" is made into a movie, I will know when to give myself whiplash and look away.

When asked by New York magazine about that scene, Bazell said: "It didn't strike me as out there at the time. But when I reread the scene a couple of months later, I felt physically ill. And I wasn't unhappy about that."

Bazell is the son of Robert Bazell, NBC News' chief science and health correspondent, and he probably doesn't feel physically ill easily. He is a resident at the University of California, San Francisco, and wrote the novel while completing his internship.

I once subscribed to the theory that you should read the book before seeing the movie. I've changed my mind about that, although I made an exception for "Beat the Reaper" because I'm a fan of medical and mob thrillers and it could be a year or two or more before a movie arrives in theaters.

I was glad I had not read "Atonement," "The Secret Life of Bees" or "Revolutionary Road" before seeing those movies, although I did afterward. Otherwise, I would have anticipated the tragic turns that lay ahead, even if the actors' faces were irrevocably attached to the names.

In December, I interviewed actor Bill Nighy, then starring in "Valkyrie" as a German general plotting to kill Adolf Hitler. Given the fate of his character, he said his challenge was "not to play the end," something he might have been tempted to do as a younger actor who brought the whole of the story with him to the stage or screen.

And if you read a book turned into a movie, you tend to play the end in your head or make a mental checklist of how they differ, which leads me to ... "The Mysteries of Pittsburgh," opening today at the Manor Theater in Squirrel Hill.

A film should not be a page-by-page dramatization of a novel, but you will enjoy "Mysteries" more if you have not read the book.

Otherwise, you will wonder what happened to the character of Arthur Lecomte and why Cleveland Arning was turned into a composite of Lecomte and the original motorcycle-riding Cleveland. That's just for starters.

Back in the late 1980s when I bought my hardcover copy of "The Mysteries of Pittsburgh" for $16.95, I had no idea it would be made into a movie and that I would be required to write about it. And write about it.

The first story appeared April 21, 2006, under the headline, "Chabon's Pittsburgh movie may not be filmed here." Along the way, there were reports that "Mysteries" would come here, that it did come here with Jon Foster, Peter Sarsgaard, Sienna Miller, Mena Suvari and Nick Nolte, and that Miller did not exactly relish her time in our fair city in fall 2006.

The lengthy time between the novel's publication and the movie production, the world premiere at the Sundance Film Festival in January 2008, single showing at the Regent Square Theater in late 2008 and, finally, its release has created an anticipation worthy of Heinz ketchup.

I wish the movie were better, although the city looks sensational and Sarsgaard and Nolte hit the high notes. So here's the bottom line: See the movie and then read the book.

Otherwise, you may feel like this passage by Chabon, which appears early in the novel: "And then we hit the Checkpoint, as Cleveland called it -- the bane of his career as one who always tried to push things; and at that inevitable one-way Checkpoint of Too Much Fun, our papers were found in order and we crossed into the invisible country of Bad Luck."

It's where good books are turned into well-intentioned but disappointing movies.