Nat Wolff is a young infantryman in Afghanistan who finds himself at odds with his sergeant (Alexander Skarsgård) and the rest of his platoon in “The Kill Team.”

Writer-director Dan Krauss has turned his documentary of the same title, about Army soldiers who called themselves “The Kill Team” for torturing and murdering civilians in the endless Afghan War that began after 9/11, into a feature film. Yes, it really happened, although this version is fictionalized. Names were changed, etc.

Andrew Briggman (Wolff) has enlisted and is about to deploy when we first meet him. Dad (Rob Morrow) couldn’t be more proud, and Andy grins at the smiles and thumbs-up he gets, just for passing through the airport in uniform.

Afghanistan is a real eye-opener, of course. Hot, dirty and dangerous work, house to house searches for men with the gear to build IEDs (improvised explosive devices). Andy follows the rules, tries to give orders to the civilians with respect, and finds himself humiliated by an outraged local.

Not to worry. His sergeant (Tunji Kasim) is a real “hearts and minds” guy, forcing his men to wave at children, handing out candy. It’s when that sergeant gets killed that the war takes a turn to an even darker side for Andy and his comrades.

Skarsgård is the replacement, Sgt. Deeks, a hardended veteran with three tours under his belt and a promise. “Give me your loyalty” and he will make them warriors,” men who will “be a part of history.”

Skarsgård plays this guy with his usually flinty intensity, speaking in an always menacing near-whisper, especially when the men get a taste of Deeks’ methods.

“Who’s ready to have some fun?”

Taking a prisoner, hiding him from command and torturing him, summary executions in the field, “incidents” that are explained away with lies. Deeks has his own playbook, his own idea of “fun.”

Most eagerly go along with it. As with any war, they have an abiding hatred of “the enemy.” As in every guerilla war, that enemy could be anyone. As in any war in a foreign land, racism finds easy acolytes among the combatants.

Andy finds himself apalled, thwarted or intimidated from reporting what he’s witnessed, coerced into participating. And with every minute that passes, we see the danger he feels for himself, a man at odds with armed men who know how to deal with “rats” and a Sgt. who seems to have getting away with all this worked out.

Krauss knows the territory, the standard operating procedures of men on and off duty, the jargon. He does a decent job at building suspense, and Wolff (“The Intern,” “The Fault in Our Stars”) gives a solid performance as a young man desperate to tell somebody what’s going on, and fearing for his life as he does.

But this is Skarsgård’s movie, and his whispered menace and gimlet-eyed stare informs his every scene. Deeks isn’t a caricature of evil. He has taken “duty” and “mission” into off-the-books and off-the-deep-end sadism.

He’s cunning and manipulative. Andy wants a promotion? He makes him fight a more qualified comrade (Brian Marc) for it in front of the entire platoon.

The big and small screens have been awash in military features and documentaries since 9/11, and there’s not a lot to “The Kill Team” that qualifies as new or surprising.

But a decent level of suspense and the genuine dread Skarsgård casts, like a shadow, inform it and make it stand out in a genre that may not outlive America’s endless military involvement in that corner of the world.

MPAA Rating: R for language throughout, violent content and drug use.

Cast: Nat Wolff, Alexander Skarsgård, Brian Marc, Adam Long, Rob Morrow

Credits: Written and directed by Dan Krauss.  An A24 release.

Running time: 1:27