If Leo goes down to the woods today, he's in a for a big surprise. He's the grizzly bear's picnic. After a terrifyingly convincing mauling, DiCaprio's frontiersman is left clawed, chewed up, spat out and barely alive. It seems the Wolf of Wall Street is no match for the Bear of Upper Shit Creek.
And thus begins the harrowing survival story of DiCaprio's Hugh Glass. A legendary frontier figure who inspired 2002's The Revenant: A Novel of Revenge which the film is loosely based on, here Glass is a wilderness guide leading a fur trapping party retreating across uncharted 1820s Wyoming mountain country after being attacked by a local tribe. The bear is but one of the hazards he faces along the way.
And so too begins The Revenant's relentless death march of a movie. It's one not so much to be enjoyed as endured, and - when its frontier realism feels a need to get metaphysical - occasionally wearied by.
But largely The Revenant is as gripping as it is grim. Much of that is down to the gutsy minimal-dialogue performance of DiCaprio driving what is a really a slight, linear story of survival and revenge.
And it's impressive too, for the savage authenticity created by director Alejandro Gonzalez Inarritu after the artifice of his 2015 Oscar winner Birdman. Though he hasn't lost all his tangential artiness in that frontier grit and ice.
Helping make this something of an endurathon are leaps into Glass' fevered imagination, including flashbacks to an earlier life among Native Americans, which produced a son who, now a teenager, is part of the expedition.
And there are Terence Malickesque visual meditations on the natural world Revenant cinematographer Emmanuel Lubezki has shot all of Malick's films since 2005 Pocahontas story, The New World all undoubtedly saying something cosmic.
Elsewhere the crisp, fluid images of scenery shot in Canada and Argentina make this an immersive wilderness experience - unpolluted by CGI other than the remarkable bear sequence - and reminds that the Old West was also the Cold West and that if the furry critters didn't get you, there was plenty of other things that could.
Among those are the Native Americans who first attack the expedition in scenes reminiscent of a flintlock and tomahawk take on the opening of Saving Private Ryan.
Escaping the fray only for Glass to be left mortally wounded by the bear, the expedition's US Army leader (Gleeson) offers a reward to two men to stay behind and tend to him or give him Christian burial.
One of those accepting the contract is Tom Hardy's John Fitzgerald, a mercenary Texan who has already expressed his dislike for Glass and his injun son. What happens next sets Glass off on his long crawl to vengeance.
That's via encounters with nasty French trappers, a kidnapped Native American woman, an extreme paleo diet plan and gruesome feats of survival. Some of those daring deeds do stretch believability. But it seems they bred 'em tough back in those days, complete with apparent imperviousness to hypothermia.
DiCaprio delivers every teeth-chattered painful grunt as if his Oscar chances depended on it, while as his nemesis, Hardy is once again convincingly mad, bad and dangerous to know.
They're a well-matched pair. Their committed performances help ground a film striving hard to be mythical, mystical and meaningful. It's not any really any of those things.
But The Revenant is still a deep dark survival thriller and a film that serves revenge as a very cold dish indeed.
Movie: The Revenant
Cast: Leonardo DiCaprio, Tom Hardy, Domhnall Gleeson
Director: Alejandro Gonzalez Inarritu
Rating: R16 (Graphic violence, sexual violence & content that may disturb)
Running time: 156 mins
Verdict: Gripping, grim Old West survival tale anchored by solid performances.