As an actor, Clint Eastwood has spent the last decade auditioning for the lead role in a remake of “The Mummy” – he’s stiff, he lumbers, and he winces at daylight. His last film as a director, “Mystic River,” was an over praised inert lump full of pretentious mannerisms. Morgan Freeman’s career has come to define “coasting”; Hilary Swank is rapidly establishing herself as a one-hit wonder. And movies about boxing are nothing more than an excuse for macho sentimentality.

Yet “Million Dollar Baby” is easily the best movie of the year. It represents a comeback for all three lead actors, as well as its director, and in a season stuffed with movies jockeying for Oscar nominations, you almost feel sorry for anyone going up against it.

Mr. Eastwood plays Frankie Dunn, a grizzled boxing trainer whose sole asset is a down-at-the-heels gym that caters to meat-and-potatoes boxers. These aren’t guys who win titles; these are mugs who get pounded on by the guys who win titles. His janitor is an ex-fighter fallen on hard times, Eddie “Scrap Iron” Dupris, played by Mr. Freeman – who, for the first time in 10 years, is called upon to actually act in a movie, rather than simply stand around like a tower of moral rectitude.

Frankie and Scrap seem happy to while away the twilight of their lives bantering in the gym, debating the merits of different brands of bleach, giving cursory training to the lackluster fighters under their care. But Frankie is torn apart when his last fighter, Big Willie (Mike Colter), decides that Frankie’s too low-rent to take him to the top and keep him there. So Frankie finds himself completely and totally alone.

Enter Ms. Swank as Maggie Fitzgerald, sporting a hillbilly accent so thick you can chew it, and with so much ambition churning in her gut that she can’t hold still. She wants to be a boxer, and she wants Frankie to be her trainer. “I don’t train girls,” he growls. But she’s a dirt-poor waitress, scraping by on minimum wage, and there’s no way to say “no” to someone who no longer has anything to lose. She keeps badgering him, and he finally takes her on.

Up until this point, “Million Dollar Baby” is indistinguishable from “Rocky,” except for its unflinching eye for detail and a sequence involving a broken nose that puts every horror movie of the past 20 years to shame for sheer seat-squirming discomfort. But Mr. Eastwood soon takes his film in disturbing and unpredictable directions. The plot is so entertaining to follow, and so hard to categorize, that it’s impossible to say more about it without ruining the audiences’ good time.

“Million Dollar Baby” is an ode to the most important thing in all our lives: work. Our lives are shaped by how we make our money and what we do with it, but Hollywood goes deaf, dumb, and blind when work is mentioned. Mr. Eastwood puts it under the microscope, however, and in his hands work becomes more compelling than an asteroid hitting the earth, more suspenseful than a plot to destroy the president, more engaging than all the pirates in the Caribbean.

I suppose it takes a director with 74 years under his belt to thrill us with nothing more than a well-told story and a couple of actors. Only a man who’s lost all his vanity could celebrate so thrillingly the beauty of calluses and scars, or proclaim that the most beautiful thing in the world is an obligation fulfilled.