Superhero movies necessarily straddle the line between extravagance and realism. When that particular superhero is Steve Rogers, aka Captain America, who fought as a medically enhanced super soldier in World War II and was frozen solid for 70 years before waking up in the present day, it would be easy to fall onto the unrealistic side. Thankfully, “Captain America: The Winter Soldier” is a skillful exercise in balance.

During this installment — directed by brothers Anthony and Joe Russo — a major shift takes place in the ever-expanding Marvel Cinematic Universe. Unlike “The Avengers,” in which the first half is plot development and the second half is a long series of stunning fight scenes, “Winter Soldier” deftly alternates action with storyline.

In many ways, “Winter Soldier” feels like a political thriller, despite the superhuman elements. The political organization in question is S.H.I.E.L.D., the Strategic Homeland Intervention, Enforcement and Logistics Division, whose mission is to protect civilians from otherworldly threats, such as the titular Winter Soldier.

The film taps into the real-world issue of governmental invasion of privacy, using technology to spy on citizens as a way to keep the peace. As Cap states early on in the film, “This isn’t freedom, this is fear.”

The action follows suit in this attempt to keep the film more grounded in reality than previous MCU films. With less CGI fighting between gods and aliens, the action focuses on impressively choreographed hand-to-hand combat.

Though Captain America has super abilities, he is not invincible, and the stakes feel legitimately high from the first action sequences.

Essential to “Winter Soldier’s” success is the caliber of the actors’ performances. While Rogers is still a relatively one-note do-gooder, Chris Evans begins to shade in more facets of the character than audiences have previously seen.

Samuel L. Jackson is given his meatiest turn as Nick Fury and does impressive work in the role, while the filmmakers dig deeper into Scarlett Johansson’s Black Widow.

Robert Redford delivers a commanding performance as Alexander Pierce, transforming what could have been a small cameo into an exciting role that helps move the machinations along. Anthony Mackie’s Sam Wilson — the Falcon — brings an easy humor to many scenes.

While not fully explored, the pathos behind the titular Winter Soldier, played by Sebastian Stan, brings the horrors of Rogers’ past into the present. A far greater threat looms behind the Winter Soldier himself, however, creating an atmosphere of great peril that is more thrilling than even the universal scope of “The Avengers.”

“Captain America: The Winter Soldier” strives not only to push its hero into new territory, but also the entire Marvel movie franchise.

A version of this article appeared in the Thursday, April 3 print edition. Jonathon Dornbush is an editor-at-large. Clio McConnell is arts editor. Email them at [email protected].