Steven Spielberg’s “The Post” throttles along in a pleasurably bustling, down-to-the-timely-minute way. It’s a heady, jam-packed docudrama that, with confidence and great filmmaking verve (though not what you’d call an excess of nuance), tells a vital American story of history, journalism, politics, and the way those things came together over a couple of fateful weeks in the summer of 1971. That’s when The New York Times, followed by The Washington Post, published extensive excerpts from the Pentagon Papers: the top-secret government history of the Vietnam War that revealed, for the first time, the lies told to the American people about U.S. involvement in Indochina dating back to 1945. (Most destructive lie: the hiding of the fact that U.S. leaders knew the war was a losing battle.)

The heart of the movie is set at the Post, where the paper’s executive editor, Ben Bradlee (Tom Hanks), with his urbane rasp, aristocrat-in-shirt-sleeves mystique, and a bite more forceful than his bark, and Katharine Graham (Meryl Streep), the paper’s wily socialite patrician publisher, square off like a couple of sparring partners who won’t let the fact that they’re on the same side stop them from taking a punch. Both of them want a great newspaper, one that will shake off its image as a “local paper” and do more than make headlines; they want it to make history. But they disagree on how to get there. The rascally Bradlee is like the prim and proper Graham’s id: She hired him, but can’t decide whether to encourage or repress him. Their contentious camaraderie is highly entertaining, and so is the whole movie, which pulses ahead like a detective yarn for news junkies, one that crackles with present-day parallels.

In 1971, following the public revelation of the Pentagon Papers, both the Times and the Post stood tall against an injunction, filed by the Nixon White House, to cease publication of the classified documents — an attempt at legal clampdown that could well have snuffed the Fourth Estate as we know it. “The Post” offers not so much a message as a warning: that freedom of the press is a fight that never stops, and that the force that keeps it going is the absolute die-hard belief in that freedom. When the press begins to accept restrictions, however grudgingly, it’s all but inviting itself to be muzzled.

That’s a lesson that has rarely needed to be heard as much as it does today. “The Post” is a movie of galvanizing relevance, one that’s all but certain to connect with an inspiringly wide audience (I predict a $100 million gross) and with the currents of awards season. That said, it’s a potently watchable movie that isn’t quite a work of art. Two of Spielberg’s recent history films were also made in a messianic spirit of topical fervor: “Munich,” a dread-inflected thriller that addressed the post-9/11 world, and “Lincoln,” a kind of dramatized time machine that commented on our own increasingly fractious and divided political arena. Yet both those films had a depth and mystery and power that transcended the moment; you could watch them 20 years from now and they would still echo. “The Post,” written by Liz Hannah and Josh Singer in a mode that’s bounding and busy and a little too expository, is a more pointedly utilitarian, less imaginative movie — it’s high-carb docudrama prose rather than poetry. You can be stirred by what it’s saying and still feel that when it’s over, the film declares more than it reverberates.

The gold standard for this sort of true-life journalistic muckraker is, of course, “All the President’s Men,” a movie that took place in the ’70s, was made in the ’70s, and tapped the alternating current of corruption and idealism that helped define the ’70s. “The Post,” by contrast, seems to be set in some fetishistic museum-piece re-creation of the ’70s, with every drag on a cigarette calling too much attention to itself (yes, a lot of people smoked — but where’s the smoky air hanging in the rooms?), too many “casually” signposted references to dinner-party mainstays like “Scotty” Reston and Lawrence Durrell, and too many actors wearing wigs that are visibly wigs (prime culprit: Michael Stuhlbarg, in a way too shiny mop, as the New York Times executive editor Abe Rosenthal). And why does Bruce Greenwood, generally an actor of supreme subtlety, blare his lines and pop his eyes as Secretary of Defense Robert McNamara, the secretly doubting hawk who commissioned the Pentagon study and then made the strategic mistake of letting someone like Daniel Ellsberg read it?

The film opens with Ellsberg, played by Matthew Rhys with a fine, forlorn rabbinical iciness, typing notes in the Vietnam combat field, then listening to McNamara on the plane ride back explain that the war is going terribly — only to watch him turn around and play the war’s booster at an airport press conference. Ellsberg is disgusted by the two faces of American policy. A research associate at the Rand Corporation, he has access to all 7,000 pages of the study, which he has spent months smuggling out, photocopying, and slipping to reporter Neil Sheehan of the Times.

Ben Bradlee can smell something is up — he’s noticed that Sheehan hasn’t had a by-line in three months — and the film hooks you with Bradlee’s cussed old-school fervor, which takes the form of his brazen desire to compete with the Times. When he and two of his reporters first see the Pentagon Papers story on a newsstand, learning about it along with everyone else, Bradlee knows how historically vital it is — but he also knows that he’s been scooped. Hanks doesn’t quite have the bone-dry gin-martini brittleness that Jason Robards summoned so memorably in “All the President’s Men,” and Hanks’ regional inflections come and go (the actor lends a Boston vowel to every 10th line or so). But he nails Bradlee’s wry and jaded WASP-renegade charisma — the star editor’s nose for truth that emerges from his acceptance of how scuzzy the world is, and how badly it needs to have the light shined on it. Despite a White House ban, Bradlee refuses to take the acerbic Judith Martin (Jessie Mueller) off the Tricia Nixon wedding, and that minor decision reflects his core values. He’s a player who’s not going to play ball.

“The Post” has some good tense scenes set in the analog era of reporting, notably when Ben Bagdikian (Bob Odenkirk), the harried Post reporter with a long-time connection to Ellsberg, hunts him down using multiple pay phones, then flies to Washington with the boxed papers in their own special seat. The shoe-leather dimension of reporting has always been more dramatic than contemporary scenes of investigators staring into their computer terminals.

At the same time, part of what rescues the movie from any vestige of preachiness is that it’s framed as a business drama. Streep’s Graham, who inherited the publisher’s mantle after her husband’s suicide, is about to take the family newspaper public, and much is made of the share price: Will it will be $24.50 or $27? That could make a difference of $3 million, which would pay for 25 reporters’ jobs. In its wonky way, “The Post” touches the first moment when people realized that American newspapers were not necessarily a growth industry. Graham’s belief — idealistic but also prophetic — is that it will be the quality of newspapers, their influence, that allows them to flourish. Streep, speaking in an imperious nasal singsong, makes Graham irresistibly knowing yet, beneath the tea-party bluster, secretly unsure of herself: the only woman in a boardroom of men, and therefore an executive who has to fly solo to find her own way.

Complicating matters is the fact that she’s close friends with Robert McNamara. Once the Pentagon Papers story breaks, will the Post go easy on him? Or will Graham follow through on Bradlee’s request and exploit the friendship to get their own copy of the papers? The answers are: No and no. But these conversations are riveting, because they transport us back to an exotic age when editors and politicians didn’t regard themselves as adversaries; they were all on the side of America. “The Post” is about how and why that era had to end. Bradlee, a former pal of JFK’s, also played the game of rubbing elbows with power. But now, disgusted by the lies revealed in the Pentagon Papers, he enunciates the new credo. “We have to be a check on their power,” he says. “If we don’t, who will?”

The movie becomes a multi-stranded tale of journalistic triumph, with Graham movingly arriving at the realization that she’s not just the caretaker of her late husband’s company; it’s her company. The decision to publish the Papers becomes nothing less than an assertion of democracy, made all the more potent when newspapers across the land publish in solidarity. The press — the media — becomes greater than the sum of its parts. But that’s because it always was. The Pentagon Papers marked an iconic moment in American history: the press claiming its own freedom to call out the excesses of power. “The Post” celebrates what that means, tapping into an enlightened nostalgia for the glory days of newspapers, but the film also takes you back to a time when the outcome was precarious, and the freedoms we thought we took for granted hung in the balance. Just as they do today.