Toying with the old adage “if you’re going to do a sequel, just make the same movie over again,” the makers of “Captain America: The Winter Soldier” have brought something distinctively new to the series while continuing—and in some sense repeating—the narrative from the excellent first installment. Joe Johnston’s “Captain America: The First Avenger” was an old-fashioned forties period piece that captured the naïve, colorful look and feel of the original comics. This follow-up from Anthony and Joe Russo brings the icebound hero into the post-Cold War world of terrorism and the paranoia it engenders, pitting Steve Rogers’ World War II-era sincerity and integrity against the sort of governmental machinations that spring from the modern tension between personal freedom and high-tech security concerns. This might be a comic book movie, but it confronts matters that in today’s geopolitical context are quite serious as well as adopting a more down-and-dirty tone; even visually it has a far darker, grittier appearance than its predecessor.

That doesn’t mean, however, that it abandons its roots in the Captain American comic mythology. The script, credited to Christopher Markus and Stephen McFeely, is basically a continuation of the good Captain’s struggle against Hydra, the malevolent organization bent on taking over the world that was the centerpiece of the previous film, and although its leader, the Red, Skull is no long with us, his toadyish underling, Dr. Zola (Toby Jones), makes a reappearance of sorts. The primary nemesis for Rogers this time around, however, is the Winter Soldier of the title—a fearsome foe with a metal arm, glaring eyes above his partial face mask, and physical prowess that rivals, if not exceeds, that of the hero. His actual identity will be well-known to comic readers (and to anyone who bothers to read the cast list and compares it to that of the first movie), but it will serve as a satisfying surprise to uninitiated viewers, and provides the obligatory link to the third part of the trilogy.

Another link to the mythology of the printed page is the addition of Anthony Mackie as Sam Wilson, a special ops veteran who takes on the mantel of the high-flying Falcon, a long-time associate of Captain America. He joins Rogers and the returning Natasha Romanoff, aka Black Widow (Scarlett Johansson) to make up the trio that takes on the still-pervasive Hydra, which plans to profit from the worldwide fear and chaos it’s promoted to establish itself as the ruling power on the planet. At its core “The Winter Soldier” is essentially a big-budget, super-hero variant on a seventies paranoid thriller, in which no one can be certain about who’s trustworthy and who’s a villain.

That’s because Hydra’s plan involves the takeover of the World Security Council presided over by Secretary Alexander Pierce (Robert Redford), which is poised to launch the ultimate planetary defense system—three huge helicarriers that can orbit earth continuously to respond to any threat. It also involves the compromise of SHIELD, the actions-ops agency for which the Captain and Natasha work, but whose head Nick Fury (Samuel L. Jackson) is attacked, and apparently killed, after he suggests postponing the launch of those huge aircraft. That sends Captain America on the lam, targeted by Hydra and by forces that might be being manipulated by them.

The plot of “The Winter Soldier” is fairly complex—with double- and triple-crosses aplenty and numerous other twists—but the script keeps the convolutions relatively clear, and the Russos are particularly adept at dealing with its more intimate elements, which they and their cast handle unusually well for this genre. The banter between Rogers and Romanoff comes off nicely as they rush about to elude the army of nefarious types out to prevent them from saving humanity, and Evans does well in capturing the air of a man out of his time as he struggles to master some seven decades of pop culture he’s missed out on. Jackson does his familiar bad-ass routine to a turn, and Mackie is appropriately stalwart as Wilson, even when he dons the Falcon’s somewhat ridiculous-looking wings. But the greatest catch of all is Redford, who seems to be enjoying playing coolly against type and whose very presence automatically calls to mind the pictures like “Three Days of the Condor” and “All the President’s Man” that this one offers a nod to.

Where the Russos prove more problematic is in the big action set-pieces—and there are lots of them, from a beginning commando raid on a ship taken over by terrorists and the explosive car chase in which Fury is injured, through the final confrontation, in which new computer chips have to be loaded into each of the three great helicarriers in order to divert disaster. The penchant for fidgety handheld camerawork by cinematographer Trent Opaloch in these sequences, along with the hyper editing by Jeffrey Ford and Matthew Schmidt, leave many of the images looking rather muddy and indistinct, so that it’s difficult to appreciate the choreography of the movements. In the more limited action moments—one in which Rogers confronts a bevy of menacing individuals in a crowded elevator, another in which Jenny Agutter, as a World Security Council member, takes out a bunch of bad-guys (before morphing into someone else entirely)—are more smoothly handled and so more satisfying.

Overall, though, the picture is technically top-drawer, with CGI effects that are genuinely impressive without dwarfing the human side of things. Henry Jackman contributes a brassy score that’s properly mixed so as not to be overpowering, though sometimes the other sound effects can be.

In sum “The Winter Soldier” manages, as the second installments of a few other big-budget trilogies (“The Empire Strikes Back,” “Superman II,” “Spider-Man 2”) did, to improve on the first chapter. It’s a rousing adventure that will make devoted fans of Captain America swoon, while also pleasing those who met him only in the first film, but also touches on some hot-button contemporary issues. As usual with these Marvel superhero flicks, there are a couple of teaser trailers in the edit credits, so you might want to stay around until the screen goes black to catch them.