In April 2003, 27-year-old thrill-seeker Aron Ralston set off for a day of hiking, mountain-biking and rock-climbing in Utah's Blue John Canyon when a falling boulder pinned his arm against the rock wall. Trapped for five days with little food or water and the knowledge that no one knew to look for him there, Ralston ultimately saved himself by amputating his own arm with a dull knife. His physically and spiritually transformative experience is dramatized to harrowing, unflinching effect in "127 Hours," director Danny Boyle's far superior follow-up to 2008's manipulative, grossly overrated "Slumdog Millionaire." At once manic and ruminative, vast and intimate, the film is as energetic as its adventurous human subject, working as both a grand entertainment and a thoughtful existential character study.

At first, everything seems to be going Aron's way. He meets two young novice hikers Kristi (Kate Mara) and Megan (Amber Tamblyn) and the three of them spend a few fun hours together as the girls tag along with this wild, mysteriously handsome stranger. A scene where they slide down a rock crevice in the earth and drop into a hidden lagoon, a serene aquatic wonderland, is breathtaking in its care-free jubilation in the face of potential peril. Before parting, Kristi and Megan invite him to a party they're throwing the following night—"Just look for the giant inflatable Scooby-Doo!" they tell him, a visual motif hauntingly revisited several times thereafter—and, with the knowledgeable viewer already aware of what is to soon happen to Aron, the film makes the sobering point of how quickly life can throw crushing curveballs into one's plans and future. Alone once more, the unthinkable happens to Aron. Naively buying into the notion of his own invincibility, his physical know-how is no match for an obstacle that proves practically insurmountable. Stranded by himself, a boulder having smashed and trapped his hand under its weight, Aron suddenly faces a situation he can't simply wiggle his way out of.

Based on Ralston's fittingly-named memoir "Between a Rock and a Hard Place," "127 Hours" is a superbly crafted, at times grueling, but always deeply compelling study of the irreplaceable, achingly mortal loves in our life, the memories we make for ourselves, and the lengths a person will go to survive. While most of the film is, indeed, occupied by just one person and a very heavy rock, writer-director Danny Boyle and co-writer Simon Beaufoy ensure that there is never a static moment, Aron's mind wandering from troubleshooting his current predicament to thoughts of his family, friends, and ex-girlfriend to full-on hallucinations when a lack of sustenance and the rough elements begin to take their toll on his physical and mental state.

Little details within Aron's ordeal, like a black hawk that passes overhead at the same time every morning, his filming of messages to his loved ones via the camera he has with him, and his savoring of sunlight that only hits him for a few minutes each day, ring remarkably true. Between these are indelible flashbacks of times past, showing his childhood bond with his parents (Treat Williams, Kate Burton) and sister (Lizzy Caplan), the good and not-so-good times between himself and girlfriend Rana (Clemence Poesy), and special experiences he's shared with friends (a scene where the lot of them cavort half-naked in a van as a snowstorm bears down outside, played out to the great song "Ca Plane Pour Moi" by Plastic Bertrand, is a bottled joy). Aron wishes he'd cherished everyone more when he had the chance—a desire heartbreaking because it is so universally relatable.

As an actor, James Franco (2010's "Eat Pray Love") continues to get better and better no matter how high he reaches. On his way to becoming a modern-day Marlon Brando or Robert De Niro—he already impeccably portrayed James Dean in a 2001 telefilm—Franco arrests the screen as Aron Ralston, playing off no one but himself for the bulk of screen time and never allowing even a second of artifice to bleed into his emotionally demanding performance. He's someone you simply cannot stop watching when he's in the frame. The rest of the compact cast fill their small roles nicely, with Kate Mara (2007's "Shooter") and Amber Tamblyn (2008's "The Sisterhood of the Traveling Pants 2"), as Kristi and Megan, so vivacious and likable in their first-act scenes that they are missed when they're gone. It's a tribute to all involved that, despite being aware of the true-life story, the viewer still hopes Aron will make it out of the canyon in one piece so he'll be able to hang out with the girls again at their party.

A very personal survival story alternating with an epic montage encapsulating the messy, wonderful beauty of one's life, "127 Hours" is alive with electric ingenuity. Topped off by a top-notch soundtrack, a vivid music score by A.R. Rahman (2009's "Couples Retreat"), cinematography by Enrique Chediak (2010's "Charlie St. Cloud") and Anthony Dod Mantle (2009's "Antichrist") so picturesque as to border on dreamlike, and excitable editing by Jon Harris (2010's "Kick-Ass") that makes exquisite use of split screens without allowing them to get in the way of the dramatic content, the film is a sensory sensation of sights, sounds and emotions. The only disappointment is its brevity; at 93 minutes, "127 Hours" is engrossing enough to have been twice as long. The climax, where Aron's fight or flight instinct comes into play through a self-inflicted amputation, is as graphic and realistic as it needs to be. Squeamish audiences will probably be covering their eyes, but this is just a tiny part of a movie about so much more than just a bloody punchline. Director Danny Boyle knows this and has accordingly made what may be his best film, to date.