“Captain America: Civil War”

Rated PG-13

*** 1/2

Opens today

“Captain America: Civil War” is an intimate epic, a giant-size comic-book movie in which people, not superheroes, steal the show. This is the biggest Marvel Studios film to date — the story plays out on a global scale, and the main cast reaches double digits — but many of its best moments are small, throwaway beats: Bucky Barnes (Sebastian Stan), who is cramped in the back of a small car, asking a surly Falcon (Anthony Mackie) to move his seat up; a star-struck Ant-Man (Paul Rudd) so giddy about meeting Captain America (Chris Evans) he practically asks for a selfie; Scarlet Witch (Elizabeth Olsen) teaching the synthetic Vision (Paul Bettany) how to properly use paprika in a recipe; Tony Stark (Robert Downey Jr.) casually flirting with Aunt May (Marisa Tomei), to the alarm of her nephew Peter Parker (Tom Holland).

Parker, of course, is the alter ego of Spider-Man, who plays an important role in “Civil War.” Black Panther (Chadwick Boseman), the African prince out to avenge the death of his father, is even more critical to the story. They haven’t been thrown in just to set up future franchises. “Civil War” expands the already daunting Marvel Cinematic Universe, but this nimble film has been so well thought out and constructed, so skillfully orchestrated and shot, it never feels overstuffed. The 2-1/2 hours fly by.

Filmmaking brothers Anthony and Joe Russo manage to do what Joss Whedon achieved only sporadically in his two “Avengers” pictures: They groove on the pleasures of a large ensemble that has been developed over the course of 12 previous movies. The whole of “Civil War” is as much fun as the scene in “Age of Ultron” in which everyone took turns trying to lift Thor’s hammer. The difference is that the characters aren’t just killing time between big action set pieces. This time the heroes are the main show, at odds over their differences of opinion about an accord that would require them to act under the supervision of the United Nations in order to cut down on collateral damage. Iron Man thinks this is a good idea. Captain America does not. The escalation builds slowly, a disagreement between friends that grows in gravity and consequence.

Borrowing the central premise (but, fortunately, little else) from the seven-issue series written by Mark Millar in 2006, “Civil War” ponders the issue of causality: As the number of superpowered beings fighting for good grows, will an equal number of supervillains rise up? There is a traditional bad guy in “Civil War” — Zemo (Daniel Bruhl) — but he has no special powers or big beams of destructive light. The script by Christopher Markus and Stephen McFeely teases out his scheme as a mystery: We don’t understand what he’s doing or why until the film is almost over. His evil plan consists of behind-the-scenes manipulation. He’s a stealth baddie, Iago instead of Thanos or Loki.

This is a bold move for a superhero movie because such films are often defined by their villains (the more daunting, the better). But “Captain America: Civil War” isn’t like most superhero movies. The Marvel films are about to get nuttier as the ramp-up to the climactic Infinity War begins, and “Civil War” feels like the Russos wanted to hit pause and bring the story back down to a recognizable reality before the action goes cosmic. The movie is deliberately paced, picking up speed as it goes, and it contains some sensational action set pieces, including a big brawl on an airport tarmac in which everybody fights everybody (the showdown exceeds your expectations) and a furious car-motorcycle chase in which the CGI trickery is so invisible, the scene feels old-school, like something out of “The French Connection.”

The big finale in “Civil War,” however, involves only a couple of characters — again, the movie goes refreshingly small — and the life-and-death stakes are grave because the film has done such a good job of stressing these (mostly) ordinary people instead of their suits. After the nihilistic deconstruction of “Deadpool” and the flattening self-importance of “Batman v Superman,” “Captain America: Civil War” reminds you how funny and exciting these films can be when they’re done right — you know, like comic books. The summer movie season has barely begun, and already the remedy for superhero movie fatigue has arrived.