It’s the age of innocence. The Avengers haven’t yet assembled. S.H.I.E.L.D are still clueless about the sci-fi threats they’ll soon be famous for fighting. And Vers – pronounced Veers – is a trainee in the Kree Starforce Military Academy, with no idea why she’s troubled by dreams of a fighter pilot past in a galaxy far far away. Appropriately enough, ahead of the Avengers: Endgame blockbuster finale, Captain Marvel is all about origins.

Vers (Brie Larson) is a Starforce Military cadet, a wannabe defender of the Kree against the shape-shifting Skrull. Her mentor Yon-Rogg (Jude Law) thinks she lacks the emotional self-control to go to war. During an ambush and capture by the Skrull, Vers escapes, only to crash land on Earth in 1995 pursued by the Skrull commander, Talos (Ben Mendelsohn), and by the ever-so-suspicious newbie agents of S.H.I.E.L.D, a young Nick Fury (Samuel L Jackson) and Phil Coulson (Clark Gregg). But nothing is as it seems.

Plus points abound. Indie directors Anna Boden and Ryan Fleck, who previously worked together on Mississippi Grind and Half Nelson, inject Captain Marvel with a whip-smart intricacy of plot, nicely wrongfooting the characters and us. A sense of the surreal works wonders in visualising Vers’ inner disorientation as she tries to sort friends from foes in her fractured memory. And some action scenes stand-out: a full-on train fight between Vers and an old lady is creepy-funny and comic-book rough.

But the directors’ lack of experience of bigger budgets and superhero helming shows up big time. Tonally the film’s off-beam. It’s like someone imitating a Marvel movie, falling flat and making you realise how beautifully judged the others are. The humour misfires. Mostly because Larson misses every comedy beat, overplaying it in word and look. Given her sassy turn in Free Fire we know she can do it. But whether dropping one-liners - having crashed through the roof of a Blockbuster video store - or in her amused double-takes, it’s all mis-timed.

Boden and Fleck even conspire to undermine their own finale. As Vers pitches into her opponents, the directors lay-on a stupid pop-song soundtrack that sucks any edginess and danger right into space. Ant-Man and Guardians of the Galaxy were funny but not when they needed to be serious. They did it right. Captain Marvel is lame in comparison, in both its comedy and action moments. It’s coming to something when a transmogrifying moggy is a highlight.

In Marvel movies the combat sequences are usually pretty nifty. Captain America upped the game, and Ant-Man and the Wasp blended athleticism with bravado choreography. Here – the train sequence aside – it’s a let-down. Larson said she trained for nine months in cardio, taekwondo, kickboxing and judo. You’d never know. Anyone could’ve done them, dully shot and play-fight light. Sadly, too Larson, is no runner. Most Marvel action heroes can kick ass. But if Endgame is relying on Captain Marvel to save the world, she needs to up her game.

Thank heavens for Samuel L Jackson, wonderfully de-aged by CGI to play a younger version of the Avengers’ franchise’s Nick Fury. A cracking performance. So too Ben Mendelsohn, almost at risk of baddie typecasting following Ready Player One, but sinister and funny here, given a greater range, even under the lizard-faced latex.

It does join the dots though about the Avengers’ origins; wittily and quietly done, for the most part. How Nick Fury got his eye patch. How Captain Marvel got her superhero name - and the ‘Avengers’ got theirs. How S.H.I.E.L.D woke up to the alien universe. And how the tesseract – the big cubic MacGuffin at the heart of Avengers: Infinity War and, presumably, Endgame - came to Earth. It’s nicely pieced together and fun for geeks. And it’s artfully shot by Avengers cinematographer Ben Davis (Guardians of the Galaxy, Dr Strange). Particularly in the perspective-bending way he evokes the hinterlands between Vers’ possible pasts.

Playing out like a female empowerment video for 12A girls, it lacks the sass and muscle of DC’s Wonder Woman and feels like the weakest of the Marvel movies. And that’s ironic – given that Captain Marvel is supposed to be the most super-powered Avenger of them all.

Filling the gap between Avenger juggernauts, Captain Marvel arrives with a degree of hype. The first of the MCU to be headlined by a female protagonist (twenty-one movies in), it offers a tasty morsel for all fans awaiting the reveal of how the Marvel heroes are snapped back together. It is a superhero film that feels more functional then revolutionary, but does gain a lot of energy from a winning central performance.

The film focuses on Vers (who also goes by the name of Carol Danvers) a supremely powerful Kree warrior. The Kree are fighting a war with shapeshifting beings known as the Skrulls. This battle leads Vers/Carol to Earth and an unknown life that may hold the key to changing the course of the galactic war she is part of. It's worth taking a moment to reflect on how successfully Marvel have crafted a franchise that has room for such elements as shapeshifting green aliens and blue-blooded warriors who fire energy out of their hands.

The best asset that Captain Marvel has is Brie Larson, who takes on the titular role with an energy and verve that immediately creates an endearing hero. Leaving an impression long after the credits have rolled, Larson has a remarkable ability to foster chemistry with each of her co-stars. This bodes well for her inclusion in Avengers: Endgame. The other performance that stands out is Samuel L. Jackson, remarkably de-aged to his Pulp Fiction heyday. A sprightly turn from the seasoned pro, there is the feeling that the actor is having a blast as a younger version of himself. Others feel a bit lost in the mix. Jude Law is affective, if underused. Annette Bening is clearly having fun, but has little material to work with. As interesting as Ben Mendelsohn is as the villain of the piece, one can't help but wish the actor would stop taking on antagonist duty. Larson really does save the day here.

Where the film falls down is offering anything stylistically or narratively to elevate proceedings above the standard Marvel fare. Whereas the very best entries in this colossal franchise bring an element to spice up the honed comic book formula (Guardians of the Galaxy brought humour and irreverence, Black Panther a delicious afrofuturist style, The Winter Soldier a 70s-tinged paranoia), Captain Marvel feels noticeably nondescript. The 90sness is fine, but nostalgia does not bring personality. At times the film feels remarkably inert, the audience being several steps ahead of the characters as Captain Marvel bobs along to its big reveals. You ache to love this hero's origin, and end up just wanting it to move along. Directors Anna Boden and Ryan Fleck bring little of the indie spark of their earlier films. It's a shame, as there is so much more that could be done here.

But at its core, Captain Marvel is a competently constructed, fitfully enjoyable blockbuster. And it is pleasing to see Marvel expand their scope beyond a certain kind of hero. Larson is a refreshing change, a promising addition to a franchise that approaches its biggest moment to date. Wherever it goes, one has to hope that there will be room for this new hero to come along for the ride.