Daniel Ellsberg was solely responsible for persuading President Lyndon B. Johnson to start a bombing campaign in Vietnam—and has spent the bulk of his post-government life regretting it. The Most Dangerous Man in America, another Oscar nominee, is co-directors Judith Ehrlich and Rick Goldsmith’s adaptation of a pair of Ellsberg’s books detailing how he became known as the documentary’s title, courtesy of Henry Kissinger.

Most viewers will already know the general story of the “Pentagon Papers,” the 7,000 pages of top-secret federal documents that proved the United States was at war with Vietnam under false pretenses. These papers were leaked to 17 newspapers by the very person who helped greenlight our country’s escalation of force.

Ellsberg, who worked under Robert McNamara, then the secretary of defense, is a frequent commentator in the film and says he leaked the papers because his conscience couldn’t take the burden anymore. He calls the initial research he gave to Johnson “the most shameful episode of my life.” And as the war dragged on and casualties skyrocketed, he saw the offensive as “unjustified homicide, and I couldn’t see the difference between that and murder. And murder had to be stopped.”

The Most Dangerous Man in America offers extensive detail on Ellsberg’s career and the circumstances that led him to his career suicide. It’s a history lesson, to be sure, but the film’s eloquent, personable, and still-sharp namesake makes it go down smooth. There’s plenty of period footage, too, which makes the directors’ decision to re-create some events—dramatic photocopying! hurried typing with coffee and cigarette at the writer’s side!—an odd if easily dismissible distraction. (A few animated scenes, though, are less forgivable.)

What really makes The Most Dangerous Man in America so gripping, though, is its obvious current-day relevance. Substitute “Iraq” for “Vietnam” and the basic facts are the same. There’s a clip of Johnson at a press conference: “I don’t want a man in here going home thinkin’ otherwise. We are going to win.” It’s all very cowboy, and very depressing. (And it’s no surprise that Ellsberg is now involved in antiwar rallies; at one point, we see him arrested during a peaceful protest.) Besides being informative, absorbing, and even a bit thrilling, the documentary leaves you with a sense of hope—which, these days, might be more important than its lessons.