The following post contains SPOILERS for Captain America: Civil War.

Avengers: Age of Ultron featured 11 Marvel superheroes.

Captain America: Civil War has 12.

In other words, this movie is crowded. Maybe overcrowded. Marvel and Sony’s new Spider-Man (Tom Holland) steals the show with his wisecracks and web-swinging, but serves almost no narrative purpose. Black Panther (Chadwick Boseman) is only slightly more important; his main function is to introduce the character to a broader audience before he gets spun off into his own standalone movie in 2018. The subplot involving the Winter Soldier (Sebastian Stan) ties up some loose ends from the last Captain America movie, but it’s not really crucial to the film’s central conflict between Cap (Chris Evans) and Iron Man (Robert Downey Jr.) over governmental control of the Avengers. The Winter Soldier doesn’t even appear in the original Civil War comics.

From a plot perspective, Civil War doesn’t need any of these guys. Reducing or removing these characters wouldn’t hurt the overarching narrative. But it would hurt the movie’s overarching theme. As messy and convoluted as Civil War’s sprawling web of supporting stars appears, every single one of them ties back to the film’s core idea. Ultimately, the movie isn’t about security or the government or abuse of power. It’s about choice.

The key choice in the movie is whether or not to sign the so-called “Sokovia Accords,” which would turn the Avengers into official United Nations peacekeepers. The pressure to sign these documents comes from the U.S. government, who feel that superheroes represent just as big a threat as the evildoers they dedicate their lives to defeating. In the wake of the events of The Avengers (where huge portions of New York City were destroyed during an alien invasion) and Avengers: Age of Ultron (in which a small European country got caught in the crossfire between the Avengers and Ultron), and the opening scenes of Civil War (where the actions of the Scarlet Witch (Elizabeth Olsen) accidentally cause numerous civilian casualties), the U.N.’s demands do not seem entirely unreasonable.

But while most of the heroes agree with the Sokovia Accords’ in theory, others argue that they will be less useful in practice. Accountability is important, but what about practicality? If they let governments dictate who they help and when, then the Avengers could become a political football, bogged down by a bureaucracy designed to prevent them doing their jobs instead of assisting them. Right or wrong, Captain America and his allies argue, some of these decisions are too important and too dangerous to be left to politicians.

Already wracked with guilt over the damage his inventions (mostly weapons) have wrought, and further ashamed when confronted by the mother of one of the men who died in Sokovia, Tony Stark is ready to become a deputized agent of the United Nations. Skeptical that politicians can be trusted to put the people’s best interests ahead of their own, Steve Rogers refuses to sign. And that schism forms the primary tension in the film.

What’s impressive about Civil War, which is surprisingly consistent on a thematic level, is the way all of its myriad subplots and side characters connect back to that central idea of choice. Not every hero has real bearing on the Sokovia Accords; not every character makes a meaningful impact on the ideological battle between Cap and Iron Man. But each one reflects in some way on the importance of personal choice and freedom in our lives.

Spider-Man’s backstory isn’t seen and is only referred to obliquely in a brief dialogue scene between Tony Stark and the new Peter Parker. Peter never mentions Uncle Ben; instead, when Tony asks Peter why he became a hero, he says “When you can do what I can do and don’t, and the bad things happen, it’s your fault.” Peter doesn’t say that great power comes with great responsibility, because this Peter doesn’t see it as a responsibility; he sees it as a choice. He chooses to fight, which explains why he accepts Tony Stark’s offer to join his team even though he’s wildly inexperienced and totally unprepared for a fight with professional soldiers like Captain America, Hawkeye, and the Falcon.

The Black Panther’s arc hinges on a series of personal choices, most importantly whether to capture or kill his father’s assassin. At first that seems to be the Winter Soldier, but he’s eventually revealed to be a pawn in a scheme hatched by Zemo (Daniel Brühl). At the end of the film, Panther finally corners Zemo and decides not to kill him, or to let him kill himself. The choices he makes next — to give asylum to Captain America and his allies, and to help care for the Winter Soldier — will have major repercussions for the Black Panther movie and the next Avengers films.

The Winter Soldier is the most tragic figure in Civil War specifically because of his lack of choice. Injured and left for dead during World War II, Bucky Barnes was rescued by Hydra and molded into a brainwashed robotic assassin. In Captain America: The Winter Soldier, he’s mostly presented as a silent, remorseless, and unstoppable killer. In Civil War, we see the actual mechanics of his programming, which is activated by a series of keywords. Once spoken, Bucky is helpless to resist, no matter who says the words or what they want him to do.

Bucky didn’t turn his back on his country; he didn’t decide to become a Hydra terrorist. He had no choice whatsoever in the matter, which makes his actions — and the wedge those actions drive between Tony Stark and Steve Rogers — that much sadder. His misfortune demonstrates the worst case scenario that Steve believes could result from the Sokovia Accords, with the Avengers becoming helpless puppets of a master with evil intentions.

The emphasis on personal choice carries through to the end of the movie, which resolves the physical conflict between Captain America and Iron Man, but not their ideological one. Throughout the film, directors Anthony and Joe Russo go out of their way to express persuasive arguments on both sides of the Sokovia Accords, and resist the urge to villainize either of the two protagonists. The Iron Man of the Civil War comics basically becomes a fascist, and even recruits super-villains like Bullseye and Venom to hunt down the heroes who refuse to fall into line. The Iron Man of the Civil War movie uses violence as an absolute last resort, and seems genuinely distraught about everything that happens. He gives Captain America chance after chance to do what he believes is “the right thing.” He doesn’t want to force him to sign. He wants him to choose to do it.

Refusing to side with either of its heroes might frustrate viewers who want there to be a clear winner and loser, but doing so extends that same choice to the audience: What would you do in Iron Man’s armor? How would you wield Captain America’s shield? Some critics might reject the film for refusing to pick a side in this debate, or for failing to insert a clear and overt political message into its downbeat ending. In this case, though, leaving things open to interpretation was precisely the point. Civil War clearly wants moviegoers to make up their own minds. It would have been inappropriate for a film this obsessed with personal choice to force a viewpoint on its fans. Just like the characters onscreen, the men and women in the theater get to choose who’s right and who’s wrong, and ultimately who’s won and who’s lost.