Seven thousand years ago, the Celestials - the cosmic deities of the Marvel Universe - dispatched a group of immortal beings, the Eternals, to Earth to protect it from an alien race known as The Deviants.
Once the Deviants were dealt with, the Eternals stayed on Earth, awaiting the order to return home.
Come the 21st Century - after 'The Blip' - the Deviants now appear to have returned.
And so it is up to Sersi (Gemma Chan), Ikaris (Richard Madden), and Sprite (Lisa McHugh) to travel the world reuniting their old comrades to face the new threat.
On the way, they will suffer great loss, learn the story of their origins, and have their eyes opened to the true purpose of their assignment to Earth.
At its heart Eternals is an intricate, complex, and fascinating story but events - despite moments of high action - unfold at a glacial pace.
That said, the narrative is sprinkled with surprise twists and revelations that ultimately make the investment of your time worthwhile.
By the end I was genuinely surprised to find myself contemplating rewatching Eternals, something that about a third of the way through I would never have entertained.
Rich in lore and backstory, the film reveals the secret history of the Marvel Universe, and had it not referenced The Avengers and The Blip it could almost stand on its own as an epic, cosmic sci-fi carved from a similar mould as 2001: A Space Odyssey.
You can feel Jack Kirby's grand scale fingerprints all over this work, which is based on a line of his comics from the 1970s.
The film also drops in some nice world-building acknowledgements of non-Marvel properties such as Batman, Superman, and Star Wars.
However, despite the nods to the established MCU this global odyssey feels largely disconnected to the earlier 20-plus movies in the franchise.
Even at the climax, when a being that would make Cthulhu look like a minnow starts to emerge from the Indian Ocean, there is no reaction from the world's superhero community. Where were the Avengers then?
Eternals is beautifully composed by writer-director Chloé Zhao, but suffers from an overblown, and unnecessarily drawn out, middle act that sees this saga padded to a duration in excess of two-and-a-half hours.
Certainly a visual treat, and not as 'art house' as I feared, this movie stands out from its kin because of vast canvas it operates over, but there's still enough of the expected fisticuffs and superpowered slugfests to retain its MCU branding.
It's just this time events, ultimately, move up to a more cosmic level (something only really hinted at in the likes of Guardians of The Galaxy and Thor), leaving mankind - in the style of true Lovecraftian horror - as insignificant ants scuttling around on our planet in blissful ignorance.
As is usual in a Marvel movie, there's a couple of intriguing mid-credit scenes laying the groundwork for future projects, one retaining the space opera vibe of Eternals with the second opening the door for Dane Whitman (the criminally underused Kit Harington) to take up the mantle of The Black Knight.