'Superhero fatigue' is a phrase commonly batted around amongst critics and forum lurkers whenever a new caped crusader is unleashed into cinemas. Cries of Hollywood running out of ideas are often heard too. Despite all of this, the likes of Spider-Man, Batman and the Avengers crew have Hulk-smashed the box office for years. Most impressively, Marvel's ever-increasing 'Cinematic Universe' has been building now for 8 years and 13 films, films that occasionally claw in over a billion at the box-office. This is not down to audiences simply flocking to the promise of CGI explosions and wise-cracks, but Marvel's insistence on keeping the formula fresh.

After a few years churning out average to above-average (and one excellent in 2008's Iron Man) origin stories for the individuals that would, in 2012, reluctantly team up to become The Avengers, producer Kevin Fiege was obviously wary of wavering interests. Marvel's work since 2014, since the mediocre Thor: The Dark World in 2013, has been exceptional, placing their heroes and villains in a variety of cinematic genres. Captain America: The Winter Soldier played out like a 70's spy thriller, casting Robert Redford to reinforce the tone, Guardians of the Galaxy often felt like bizarre B-movie with a bigger budget and a more talented cast, and Ant-Man, a movie many predicted to be a disaster, was a full-on comedy, bolstered by the presence of an effortlessly charming Paul Rudd.

The latest - and by far the best - is the third and possibly final entry into the stand-alone Captain America series. Retaining The Winter Soldier's directors Anthony and Joe Russo and also much of the same tone, Civil War pits its second most popular superhero against its first, Robert Downey Jr.'s Iron Man. Also along for the ride is almost every other hero on the roster, along with a couple of new ones. But what makes Civil War very much a Captain America film and not The Avengers 3 is the Russo's remarkable grasp of their characters. With Bucky Barnes aka The Winter Soldier (Sebastian Stan) back on the scene as a very wanted man, Steve Rogers (Chris Evans) finds himself torn between his loyalty to an old friend and being held accountable for his superhero actions. It is the friendship between the two that remains at the heart of the film.

When Scarlet Witch (Elizabeth Olsen) accidentally causes mass destruction in Lagos on a mission led by Captain America, the Secretary of State Thaddeus Ross (William Hurt) informs the Avengers that the United Nations are passing a bill known as the Sokovia Accords, which will see them under the control of a UN panel. Full of guilt over his balls-up with creating Ultron, Tony Stark backs the bill, as do War Machine (Don Cheadle), Black Widow (Scarlett Johansson) and Vision (Paul Bettany). With little confidence in the government, Steve opposes the bill, and is followed by Falcon (Anthony Mackie), Scarlet Witch, Hawkeye (Jeremy Renner) and Ant- Man. Tensions are raised higher when The Winter Soldier is accused of bombing the UN conference in Vienna and becomes a wanted man all over the world.

What makes Civil War such a gripping film is its refusal to offer any easy answers. Depending on your own political and personal views, Captain America could be the antagonist of his own movie, causing a war between friends over his blind loyalty to a friend he knows is a mass-murderer, albeit a brain-washed super soldier experiment. On the flip-side, the character Downey Jr. has now immortalised and the hero to always receive top billing could become a knee-bending traitor seeking accountability for his own irresponsible actions during the events of Age of Ultron. More likely, and more interestingly, you will come to realise that there is simply no right answer.

So it all comes down to who wins the fight. And what a fight it is. One of biggest flaws of Batman v Superman was its failure to come up with a believable scenario that would cause the good guys to beat on each other only to come to realise they are on the same side. Not only does the brawl feel organic, taking place at Leipzig airport with each character allowed more than one moment to shine, but it also refuses to offer any easy solution or a big bad for the team to unite against. The motivation and plan of the film's villain, Helmut Zemo, played with a remarkable subtlety by Daniel Bruhl, is kept a mystery until near towards the end. And just when you think you finally know where it's all heading, it side-steps you and goes in a completely different direction.

The film's biggest flaw is the introduction of Spider-Man, who is finally back in the hands of Marvel after Sony's failure to re-boot the franchise with Andrew Garfield. Played by Tom Holland, who is the best Peter Parker yet, his entry into the fold feels shoe-horned and slightly awkward. But when he is let loose during the airport fight, he damn near steals it until Ant-Man shows his new friends just what he can do. The other newbie, Black Panther aka the Wakandan T'Challa (a gravelly Chadwick Boseman), plays a bigger role than you might expect, still learning and developing into the king he will become. Above all else, Civil War is simply a blast. With such care taken with its army of characters, each getting their own arc, its easy to become emotionally invested. So when Cap and Iron Man really get down to business, it becomes unbearable to think that one of them may not walk away. Bravo, Marvel and the Russo's.