This is going to sound strange, but bring something to bite down on when you go see 127 Hours.

I say this because I wish I had something sturdy to stick in my mouth during some of the more intense moments of Danny Boyle's new film. It might have lessened some of the squirming in my seat. The "action" gets hardcore, and by the time it does, you will be so thoroughly invested, you're going to feel it.

There is not a lot of plot to dissect with 127 Hours. It is based on the true story of Aron Ralston, a biker and mountain climber who, in 2003, fell down a crevasse in Utah and got trapped. His right arm was pinned by a rock, and he was stuck there, standing upright on another rock a couple of feet off the canyon floor. The opening he fell through was several body lengths away, and there was no one around for miles. For the next five days, he tried to release himself while also trying not to go crazy from seclusion and starvation. He only had enough water for two days, and less than that on food. Eventually, the only measures left were drastic ones. (It seems strange worrying about spoilers for a story that was all over the news for the very tidbit I'm not spoiling, but since there is no need to discuss it here, I won't.)

127 Hours is adapted from Ralston's book about the experience, Between a Rock and a Hard Place. The script is by Boyle and Simon Beaufoy, the team behind the cynically slick Slumdog Millionaire. Boyle has proven himself an inventive filmmaker over the years, invigorating movies as diverse as the junkie crime film Trainspotting and the genre redefining 28 Days Later. 127 Hours is kind of a strange cousin to one of Boyle's most recent films, the underrated Sunshine. In that movie, the director used the confined quarters of a spaceship to detail how seclusion could drive men to madness. 127 Hours is more down to earth--quite literally--but the experience of already having navigated a tight space serves the filmmaker well.

James Franco stars in the film as Aron, and it is essentially a one-man show. The only other places Boyle goes to once Aron is trapped are the places the climber visits in his mind. He is plagued by hallucinations when he's awake, and nightmares about his predicament when he is asleep. Boyle warps the fabric of his reality so we aren't always sure which is which, with Franco's reactions often being our clue to puzzling it all out. Boyle and his duo of cinematographers, Enrique Chediak (Repo Men) and Anthony Dod Mantle (Antichrist), use multiple cameras and create a sense of movement by switching between shooting styles. Aron also kept a video diary during his ordeal, and so that provides an added set-up. Franco particularly shines in these moments. It's just him and the imaginary audience in his mind.

You're going to be amazed by what a cracking movie 127 Hours is. It might be hard to imagine how a script with such limited scope could remain interesting for more than 90 minutes, but trust that these talented people have figured out how to do it. Fair warning, though, as noted at the start, there are scenes that are not for the squeamish. 127 Hours is never gratuitous or exploitative, but it does feel very real. The fact that you grow to like Aron (and get to know every pore and orifice on James Franco's face) means that the physical anguish also has tremendous emotional impact. Anyone with claustrophobia may also find the movie too severe. If, for instance, you've had problems with other cave-dwelling films like The Descent, you might want to check yourself before you buy a ticket.

For everyone else, though, 127 Hours is more than worth gritting your teeth and bearing it. It's a genuine must-see for the fall season.

Jamie S. Rich is a novelist and comic book writer. He is best known for his collaborations with Joelle Jones, including the hardboiled crime comic book You Have Killed Me, the challenging romance 12 Reasons Why I Love Her, and the 2007 prose novel Have You Seen the Horizon Lately?, for which Jones did the cover. All three were published by Oni Press. His most recent projects include the futuristic romance A Boy and a Girl with Natalie Nourigat; Archer Coe and the Thousand Natural Shocks, a loopy crime tale drawn by Dan Christensen; and the horror miniseries Madame Frankenstein, a collaboration with Megan Levens. Follow Rich's blog at Confessions123.com.