A few years ago in 2014, Marvel Studios turned some of the oddest lesser-known comic-book characters into smash-hits with Guardians of the Galaxy, a spacefaring movie about a talking raccoon, a friendly tree, an obnoxious human and a few aliens who saved a planet together and became beloved pop culture heroes in one fell swoop.

There was a certain swagger in the commission from Marvel – clearly, there was no dark, hidden corner of their back catalogue that they couldn’t turn into a hit. Now, years later they’ve delved even deeper into their intellectual property collection for Eternals, a kind of fantasy-superhero epic based on comics by Jack Kirby (and a more modern run on the characters by Neil Gaiman).

But this time, it’s possible that Marvel might have bitten off more than they can chew, delivering a long, dense and sometimes drab film that has its moments, but overall lacks some of the energy of the wider Marvel Cinematic Universe.

The story begins thousands of years ago, when the Eternals – essentially good-looking aliens from the planet Olympia, complete with their own specially-defined powers – arrive on Earth to protect us all from twisted monsters called the Deviants. This is explained in the film (in a bit of a first from Marvel) with a Star Wars-style opening crawl that lays out some of this world-building.

A quick roll-call gives us team leader Ajax (Salma Hayek), a healer who also communes with their godlike Celestial boss Arishem; Ikaris (Richard Madden) who can fly and has heat vision; Sersi (Gemma Chan) who can change the property of objects, like stone into metal; Sprite (Lia McHugh), who can cast illusions; Gilgamesh (Don Lee) who has magical gauntlets and super strength; Thena (Angelina Jolie) a great warrior who can summon energy weapons; Makkari (Lauren Ridloff) a super-speedster; Druig (Barry Keoghan) a mind-controller; Kingo (Kumail Nanjiani) who can fire blasts of energy; and Phastos (Brian Tyree Henry) who can control and create advanced technology from the air.

If this seems like a long list of characters to get to know, you’d be right – and given that they all already know each other, audiences have a while to catch up with the relationship dynamics, rivalries and alliances between the group, who in the present day have disbanded after killing the last Deviant centuries before.

Or so they thought – because when a new, more powerful Deviant attacks Sersi and her new boyfriend Dane (Kit Harington) in London, the Eternals have to come together again to face the new threat. To say more about the story would delve into spoiler territory, but suffice to say there are plenty of exciting action scenes as the Eternals show off their abilities, globetrot to different locations and face off with deadly foes.

These action sequences are some of the strongest parts of the film, with the well-defined and complementary abilities of the team used regularly and in different situations. Sure, sometimes their divided powers are a little too neat – like how the Teenage Mutant Ninja Turtles get a special weapon each (and one of the Eternals even “does machines”) – but there’s also clarity in it, and it’s easy to imagine kids in the playground deciding who gets to play as each character.

It’s also a credit to the film that every character in this heaving cast gets a moment to shine. While Chan’s Sersi is undoubtedly the main character none of the team are underused, with the possible exception of the mischievious Makkari (who appears mainly in flashbacks until the film’s grand conclusion).

As the preening Kingo, Nanjiani is a particular stand-out, though Brian Tyree Henry delivers some of the most powerful emotional moments later in the film. Harington (in the film a lot less than you might think) plays a lighter, more comedic role than fans of Game of Thrones will be used to, but he’s likeable in those small doses, and the film hints at a bigger role for him as the MCU grinds on.

There’s lots to like about the film. The issue is that over the course of its long runtime (it lasts two hours and 37 minutes, around half an hour longer than the recent Shang-Chi) there’s a strange kind of distance to the characters, a listlessness and lack of life that no amount of flashy, glowing battles can disguise. Director Chloe Zhao’s much-vaunted natural lighting techniques possibly don’t help with this – a lot of the time scenes just seem dark or drab – and with the exception of a few gags from Nanjiani or Tyree Henry, the characters seem a bit wet and mopey.

There’s just so much exposition and explanation to get through and so many characters to focus on that it’s initially hard to warm to any of them. By sheer force of time spent on-screen (helped by that runtime) this distance does abate gradually, and a strong final act helps make for a satisfying conclusion, but overall it’s not the slick, cheering Marvel experience that audiences have become used to.

Frustratingly, it does sometimes feel like there’s a version of this film that could have worked better – a version where it relied less on flashbacks, or where the Eternals’ importance to the world felt more pronounced, or the whole thing wasn’t so listless at times – but in the finished version, it remains stubbornly out of reach.

Eternals isn’t a bad film. It has entertaining moments, the requisite post-credits scenes and plenty of big-budget superhero action. There are good performances and not-so-good performances, moments where everything comes together perfectly and moments where it all hangs by a thread.

But there’s no denying it’s not the absolute triumph Marvel will have been hoping for. Still, not everything can be Guardians of the Galaxy. Whatever the next big swing from the studio is, hope springs eternal.

Eternals is in UK cinemas from Friday 5th November. For more, check out our dedicated Sci-Fi page or our full TV Guide.