Alex Gibney, best known for documentaries such as “Taxi to the Dark Side” and “Going Clear,” is helming a new feature starring Viggo Mortensen (“Captain Fantastic”) and Cannes best actor winner Caleb Landry Jones (“Nitram”).

Produced and sold internationally by Altitude, thriller “Two Wolves” will be introduced to buyers at the virtual American Film Market next week. All rights are currently available. Domestic Rights are co-repped by UTA Independent Film Group and ICM.

Here’s the official description: The film tells the story of helicopter pilot Hugh Thompson who, during the Vietnam War, turned against his fellow soldiers to halt the massacre of unarmed civilians in the village of My Lai, and rescued survivors of the atrocities. But far from being treated as a hero, Thompson was branded a traitor and threatened with court-martial, while the actual perpetrators of the war crimes were lionized by supporters and pardoned by President Nixon. It came down to General William ‘Ray’ Peers to investigate what really happened at My Lai and to corroborate the truth of Hugh Thompson’s story … a truth for which both men were willing to fight despite the enormous risk to themselves. What was at stake? The soul of a country and the end of the Vietnam War.

“Two Wolves” is written by two-time Oscar winner Anthony McCarten (“The Theory of Everything”) and Matt Cook (“The Informer”). The film will be produced by Paul Higgins for Fields Park; Peter Saraf and Will Clarke for Altitude Film Entertainment; and Gibney for Jigsaw Pictures along with Big Beach.

An Oscar winner for 2007 Afghanistan war documentary “Taxi to the Dark Side,” Gibney’s recent films include “Citizen K,” “The Inventor: Out for Blood in Silicon Valley” and “Rolling Stone: Stories From the Edge.” While he has directed episodes of scripted shows such as “Billions,” the vast majority of his work has focused on documentary. One of his earliest credits, however, is the feature film “The Ruling Classroom,” which he co-directed with Peter Bull.

“This is a film I have wanted to make for seven years,” said Gibney. “Now that I have the right team in place, we can tell this powerful tale. It’s a true story about how everyday people can become heroes, not through supernatural powers, but through a commitment to do the right thing in the worst possible circumstances. Since ‘Enron,’ I’ve been making films about people who abuse their power. This is film about two men who fought back.”

Producer Higgins added: “The message of ‘Two Wolves’ is a powerful one. It implores us to consider the importance of the right leaders; the importance of the truth; the importance of learning from our mistakes or being forever destined to repeat them. It explores the need to listen to the better angels of our nature and, the notion that one man can make a difference. There has never been a more pertinent time for this story to be told.”