A scene from Lone Survivor.

Lone Survivor, an explosive passion project from writer-director Peter Berg, takes an unrelentingly gruesome look at Operation Red Wings, the failed 2005 mission in Afghanistan that claimed the lives of 19 American soldiers.

Autopsies and first-hand witness accounts have revealed that three Navy SEALs were brutally killed by bullets and the rugged countryside tearing them apart. As for the other 16 soldiers killed, they died when a Taliban rocket-propelled grenade struck their helicopter and sent them crashing into a cliff.

Most of the movie centers on the four Navy SEALs dropped into hostile territory, and how an unfortunate civilian encounter and communications problems led to a massive gun battle with insurmountable odds.

In a performance that stands among his best, Mark Wahlberg plays Marcus Luttrell, the Navy SEAL who co-wrote the book upon which this movie is based. (The real Luttrell actually has a cameo early in the film; he acted as a consultant.) Luttrell and fellow Navy SEALs Michael Murphy (Taylor Kitsch), Danny Dietz (Emile Hirsch) and Matt Axelson (Ben Foster) were performing reconnaissance for a mission meant to capture or kill a notorious Taliban leader when a trio of goat herders stumbled upon their camp.

In a powerfully acted scene, the four men debate whether or not they should let these prisoners go, or “terminate the compromise.” Their decision ultimately leads to a skirmish wherein they are far outnumbered.

This is where Berg and his stunt-and-effects crew really go to work. Aided in part by Greg Nicotero, who does the makeup effects for The Walking Dead, Berg shows injury after injury; it’s a true horror show. When the actors take hits in this movie, they sound very real—and extremely painful. This is especially true during two sequences in which SEALs must evade bullets by jumping off cliffs. These plummets feature stuntmen crashing into rocks and trees with a ferocity that looks positively deadly. Berg seamlessly injects edits of the actual actors falling as well.

There’s a story circulating (told by both Wahlberg and Berg) that the first stuntman to leap off a cliff for Lone Survivor broke a bunch of ribs, punctured his lung and had to be airlifted off the set. When you actually see how jarringly realistic this movie is, you’ll be shocked the stunt guy’s injuries weren’t worse.

The last act of the film depicts how some sympathetic Afghani villagers found one of the SEALs and sheltered him from Taliban forces until Americans arrived. Don’t think this part of the film represents anything near relief, because the SEAL endures plenty of pain and near-death episodes during this stretch, too.

This film features one of the best acting ensembles of the last year. Wahlberg leads the group with fury, as well as the occasional—and much-needed—humorous touch. Kitsch, who recently headlined the Berg stinker Battleship and starred in the ill-fated John Carter, experiences a complete career resurrection here. He offers a strong, sympathetic presence as Murphy.

Hirsch, so good in the recent Prince Avalanche and The Motel Life, breaks hearts as Dietz, who loses his drawing hand during a battle. Foster is perhaps the most powerful of the bunch as a man who actually gets shot in the head, yet keeps on fighting.

Lone Survivor pulverizes the senses and features good actors at the top of their games, giving the film the sort of emotional anchor sorely missing in too many military-based movies. The men here don’t die waving American flags accompanied by “The Battle Hymn of the Republic.” They die some of the hardest, loneliest deaths you will ever see—and that fact is all the more horrifying because these deaths are steeped in reality.

Lone Survivor opens Friday, Jan. 10, at theaters across the valley.