The Avengers are on a mission to protect the innocent, but end up being blamed for the collateral damage to civilians. They are forced by the United Nations to sign themselves over to be babysat by bureaucrats who say they can't be trusted, have too many gadgets and are far too trigger happy.
Should they succumb to the suits? Or should they go rogue and become wanted criminals?
The group is ideologically divided, which manifests itself in snippy philosophical conversations and enormous fight scenes between some of the most famous superheroes of the big screen.
But these big-billing Iron Man versus Captain America battles are no gimmick, and are handled with all the excitement, tension and spectacle needed to deliver satisfying blockbuster action.
After the head-in-a-blender nightmare that was Batman v Superman, everything in Civil War feels infinitely crisper, sharper and handled with far more care.
Marvel fans will delight at the return of old favourites, from the Black Widow (Scarlett Johansson) to War Machine (Don Cheadle) and some new, revived characters that help make the universe all the richer.
Make no mistake, this is a movie for the fans. If you are coming into the story with no prior knowledge, the film doesn't make any attempt to hold your hand. Forget being spoon-fed a whole lot of backstory. Instead expect established relationships developed from the previous films.
You might have to do some homework, but the experience will be all the better for it.
From nods to coming films and barbs at the past, it's refreshing to see a film franchise so confident in its audience, and so assured in its characters.
Despite its air of whimsy, Civil War never leaves much time between bone-rattling punching and explosions.
As nimble as Captain America himself, the film flits between earnest conversations and physical comedy, the awkwardness of the new recruits and the slickness of the old hats.
It even makes a joke of itself.
Directly responding to past criticisms of the Black Widow's lack of character development, she is pointedly given centre stage in the first solo fight scene. It's overblown, kickass and possibly the geekiest in-joke of all time.
Captain America: Civil War turns The Avengers inside out, forcing conflict between the characters while managing to stage big action set pieces and even bigger jokes.
No one makes popcorn blockbusters like Marvel right now. Head along. And be sure to stay to the end credits.
Rated: M
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