Chris Evans and Scarlett Johansson reprise their roles as Captain America/Steve Rogers and Black Widow/Natasha Romanoff in “Captain America: The Winter Soldier,” the newest installment in the Avengers superheroes series. (Zade Rosenthal)

Crash, boom, bang.

Captain America: The Winter Soldier” brings back one of the most mild-mannered superheroes of the Marvel Avengers franchise, the clean-cut, square-jawed Steve Rogers, whose quiet determination and commitment to decency — oh, and preternatural speed and strength — allow him to speak softly and carry a big shield.

But in this, the second installment featuring Rogers and his titular alter ego, Steve is forced into all manner of chaotic, cacophonous action. A baggy, at times brutal conglomeration of surprisingly deep character development and aggressively percussive action, “The Winter Soldier” is a comic-book movie only in its provenance. (The character was created by Marvel back in 1941.) In its relentless violence and dark political subtext, this might be the most grown-up Avengers episode yet.

“The Winter Soldier” finds Rogers — now fully defrosted after being cryogenically preserved during World War II — jogging around the Mall; it’s been two years since the near- destruction of New York City (the climactic set piece of shared-universe lollapalooza “The Avengers”), and he’s still trying to get up to speed on such late-20th-century developments as grunge music and Thai food. After striking up a friendly conversation with fellow runner and war veteran Sam Wilson (Anthony Mackie), Steve is picked up by Natasha Romanoff (Scarlett Johansson): They’ve got a job to do, this time involving nonchalantly saving a ship and the lives of the S.H.I.E.L.D. operatives who have been taken hostage on it.

Just another day’s work for the savior of the Western World, but straight-arrow Steve suspects that something’s up when Natasha seems more concerned with saving the ship’s computer data to her flash drive than fighting the Algerian terrorists swarming the boat. It turns out Steve has reason for suspicion, as “The Winter Soldier” proves that, even back at S.H.I.E.L.D. headquarters in what seems to be Northern Virginia’s coolest — if vaguely fascistic — office complex, no one can be trusted.

One of the great strengths of the Avengers mega-franchise has been its canny casting, and “The Winter Soldier” is no exception: Chris Evans once again brings a clean-cut, straight-shooting air of simplicity to Steve’s principled paragon, even evincing a whiff or two of prissy self-righteousness along the way. Happily, directors Joe and Anthony Russo, working from a script by Christopher Markus and Stephen McFeely, have decided to make “The Winter Soldier” something of a two-hander between Steve and Natasha, who as portrayed by Johansson continually threatens to steal the entire movie with her slinky martial arts moves and sultry, smoky-voiced one-liners. (If Hollywood was waiting for proof that the Black Widow was ready for her own installment, here it is. Get cracking, fellas.)

Other beloved S.H.I.E.L.D. figures are on hand here as well, including Nick Fury (Samuel L. Jackson) and Maria Hill (Cobie Smulders), and viewers might want to brace themselves for a loss that rivals the death of Maria’s old work buddy, Clark Gregg’s still-lamented Phil Coulson. But it’s the newcomers who make the biggest impact in “The Winter Soldier,” especially Robert Redford, who plays Fury’s longtime colleague and World Security Council leader Alexander Pierce with cagey charm and cool reticence; and Mackie, who convincingly introduces a new character, the Falcon, with appealing, unforced charisma and the grace of a titanium Icarus.

For a script that presumably has been in development for more than a few years, “The Winter Soldier” uncannily taps into anxieties having to do not only with post-9/11 arguments about security and freedom, but also Obama-era drone strikes and Snowden-era privacy. Indeed, there are moments that, in their taut writing and ingenious staging, recall the icy-hot paranoid thrillers that Redford himself made back in the 1970s.

But lest audiences think that “The Winter Soldier” will fall into the trap of taking itself too seriously, the filmmakers make sure that for every serious motif there’s at least one joke (a scene set in a bunker full of ’70s-era computer equipment is particularly piquant, as is a terrifically legit-looking Air and Space Museum exhibition devoted to Steve’s career) and one-and-a-half scenes of pulverizing, knuckle-splitting action. At a running time of over two hours, “The Winter Soldier” easily could have trimmed its long-winded action set pieces, extravaganzas of promiscuous gunplay, all-engulfing fireballs and loud lashings of shattered glass that begin to feel repetitive by the film’s Big Finish, a fight that plays out with over-the-top violence that’s both cartoonish and repellently brutalizing.

For all of its overstatement, though, “The Winter Soldier” is superbly made and well-acted, neatly setting up the next few installments with just the right enticing sense of ongoing mystery. As ever, perhaps the biggest lingering question has to do with whether S.H.I.E.L.D.’s sharp-elbowed superheroes will work together as a functional team or go their own idiosyncratic ways. As “The Winter Soldier” proves, often with a punishing vengeance, just because you share a universe doesn’t necessarily mean you play well with others.

★ ★ ★PG-13. At area theaters. Contains intense sequences of violence, gunplay and action throughout. 136 minutes.