Twelve films and a bit over $9 billion in box-office receipts later, it can be hard to remember a time when the prospect of a Marvel Cinematic Universe felt like a huge gamble. But back in 2008, Iron Man was more or less exactly that: a mid-budget blockbuster from an untested studio, starring an actor of then-uncertain pulling power, and centering on a character with then-untested mass-market appeal. In short, it was exactly the kind of risk that Hollywood almost never takes any more. Why not? Because it’s too busy making films like Iron Man. Eight years on from that initial bet, Captain America: Civil War is the point at which the Kilimanjaro of chips Marvel has accrued since are triumphantly cashed in. Civil War isn’t just the 13th and latest Marvel Studios film, but the franchise’s long-quested-for peak.

Joe and Anthony Russo’s film asks you not just to thrill to the escapades of its 12-strong superhero ensemble, but to invest in them as deeply as you would the leads in a long-form serial drama. In doing so, it draws on entire films’-worth of groundwork, detonating emotional time-bombs you didn’t even know had been rigged. If you’ve been following the story so far, but still doubt you could get misty-eyed over Captain America/Steve Rogers (Chris Evans) and Iron Man/Tony Stark (Robert Downey, Jr.) knocking CGI stuffing out of one another in a Siberian bunker – well, here is the film to prove you wrong.

The extensively trailed Cap vs Iron Man title fight is prompted by an ideological split at Avengers HQ. The UN wants to bring our heroes under control and one six-strong faction, led by Stark, and including Scarlett Johansson’s now-indispensable Black Widow, readily signs up. But half a dozen more; Rogers, Bucky Barnes (Sebastian Stan), Falcon (Anthony Mackie), Scarlet Witch (Elizabeth Olsen), Hawkeye (Jeremy Renner) and Ant-Man (Paul Rudd) go rogue, sensing malign forces at work. Naturally, they’re right: a mysterious doctor (Daniel Brühl) is digging into Bucky’s past as a Hydra assassin, and particularly a 1991 mission, which the film revisits in fog-wreathed flashbacks. Discord is part of the plan. It appears that newcomers will be hopelessly lost, but that’s part of the Marvel fun. The time for introductions was years ago: when the new Spider-Man (a scene-stealing Tom Holland) shows up, he excitedly starts to recount his now-threadbare origin story, only to be cut off by Downey, Jr. before he gets to the radioactive bite.

All the background the film gives you to cheer on franchise newcomer Black Panther (Chadwick Boseman) and it’s more than enough comes in two taut scenes between the Wakandan warrior prince and his father (John Kani). Boseman delivers his dialogue in a coiled East African purr that rounds out his character as quickly and evocatively as Stark’s garrulous Manhattan twang. The film may be two-and-a-half hours long, but it’s surprising how little time is wasted. The script, by Christopher Markus and Stephen McFeely, is structured like a great all-day Netflix binge, with capacious, character-building dialogue scenes and a constant drip-feed of revelations and twists. (The great lesson of Shane Black’s Iron Man 3 – that these characters are invariably more interesting out of their suits – remains well-learned.)

Throughout, the control of tone is pin-precise. The film’s centrepiece action sequence, a six-on-six battle royale on a German airfield, feels like the lavishly enjoyable last word on a thousand “who would win in a fight between…” playground arguments, while Downey, Jr. and Evans’s climactic battle, though it deploys much of the same computer-generated whizz-bang, is startlingly heavy with heartbreak. At the root of that is Civil War’s greatest strength and the reason it makes all thought of the recent Batman v Superman debacle evaporate on contact. The Russos’ film has an unshakeable faith in these decades-old characters: they’re not wrangled into standing for anything other than who they are, with no gloss or reinterpretation or reach for epic significance required. This is the cinematic superhero showdown you’ve dreamt of since childhood, precisely because that’s everything and all it wants to be. We would safely dare say that there has been no equally spectacular movie as Civil War, it’s the most emotionally compromising superhero film we’ve ever seen in our lives.