An epic poem carved in flesh and written in blood, “The Revenant” is the American frontier myth as it really was — venal and brutish, murderous and vengeful.

It makes for a great film, an American classic and one of the best movies of 2015.

Director Alejandro González Iñárritu (“Birdman”) transforms Leonardo DiCaprio into not just a mountain man, but a man in full — hoarse, battered, broken, but kept alive by one thought — avenging himself on the man who left him for dead.

DiCaprio is Hugh Glass, guide for a team of trappers who are ambushed by Indians in the West of the 1820s. He is no superman, and is no more responsible for the survival of those who escape than their captain (Domhnall Gleeson) and sheer luck.

Glass once took an native woman for a wife, and his son (Forrest Goodluck) is the only survival of that union. But as the party is chased by natives and races the coming winter, misfortune dogs Glass. A horrific bear attack, and that should be all she wrote.

“What you holdin’ on to, Glass? You ready to take the Sacrament?” trapper John Fitzgerald (Tom Hardy) wants to know. “I could do that for you.”

The racist and murderous Fitzgerald and Glass have been feuding over everything bad that has befallen the company. The guide’s grievous wounds are the only excuse Fitzgerald needs. If he can just get the man’s son out of the way.

The burly, surly Hardy has instant credibility as Fitzgerald. It is DiCaprio, and the vivid, horrific and realistic (digital) bear attack that are the picture’s hard sells. The actor, whose character is rendered almost mute by his ordeal, benefits from the silence and the hoarseness that follows.

The survival epic takes Glass across the wintry wilderness, into contact with friendly (and unfriendly) natives, and DiCaprio is convincing in every frame. The boyish voice and baby face, evident even in “The Wolf of Wall Street,” disappears behind grimaces, torn skin, blood and fur.

Gleeson is considerably more at home here than in his villainous supporting role in “Star Wars: The Force Awakens,” a performance that required him to do a lot of pacing with his hands behind his back. The British actor Will Poulter (“Son of Rambow,””We’re the Millers”), playing another member of the fur trapping party, is the very embodiment of greenhorn — slow to lose the values, and the baby fat — of the civilization he left behind.

This is the most fascinating corner of frontier history, before the trails had been blazed, before civilization stuffed cattle, cowboys, school marms and men with guns, some with badges, into the West. Inarritu revels in the simple wildness of it all — tall trees, raging rivers, snowswept prairies.

The color palette is all rustic browns and red blood as befits the primal story being told. This is Biblical, a world before law, where justice is “an eye for an eye.”

And Inarritu gets that, delivering a riveting saga of pain, grit and the brute moral relativism of revenge, the first law of all, and the only one that mattered back then. “The Revenant” is one of the best pictures of the year.
MPAA Rating: R for strong frontier combat and violence including gory images, a sexual assault, language and brief nudity

Cast: Leonardo DiCaprio, Tom Hardy, Domhnall Gleeson, Will Poulter, Forrest Goodluck
Credits: Directed by Alejandro González Iñárritu, script by Mark L. Smith and Alejandro González Iñárritu, based on the Michael Punke novel and the 1971 film “Man in the Wilderness.” A 20th Century Fox release.

Running time: 2:36