The line between a triumphant comeback and selling out has always been a slender one. For every great band that returns to their fans artistically invigorated, another plods along global tours offering up tired renditions of old classics for a gradually-diminishing paycheque. Walking into Alien Covenant, Ridley Scott’s latest in the long-gestating Alien franchise, I admit to expecting something closer in spirit to the latter.

After all, Prometheus didn’t suggest any grand ambition to do much more than sell tickets. Despite its ostentatious title and the mystery surrounding its release, that film struck me as a gussied-up slasher film. Not a bad film, but inevitably disappointing when compared to the legacy of Scott’s original film and James Cameron’s bombastic sequel.

It was a surprise, then, to find that the biblical import of Covenant’s title was more than just grandstanding lipservice. Yes, the outline of the narrative is basically a rehash of Prometheus; we follow a ragged crew of intergalactic colonists whose ill-advised sojourn to the surface on an unfamiliar planet proves disastrous. Yet Scott uses all the black goop and snarling xenomorphs to stage an earnest, ambitious feint at grand philosophical themes. This is a film that’s as interested in the fundamental purpose of humanity as it is in vivisecting its human characters, and the end result is idiosyncratic and weird in a way that so few franchise film are.

Alien Covenant is a Ridley Scott film as much as it is an Alien film. That auterist ambition renders it a breath of fresh air in today’s increasingly homogenous blockbuster landscape. A blast of chilly air, though; Covenant’s philosophical approach drains it of much of the suspense and horror that defined its terrifying forebear. There’s plenty of viscera and violence, but Scott regards it with a curiously dispassionate – even robotic – tone.

That deliberately distancing tone feels like a deliberate choice, and one of many that elevate the film above Prometheus. That film was widely criticised for the supposed stupidity of its characters, who removed their helmets in unfamiliar environs and even playfully engaged with what turned out to be a particularly-devastating biological weapon (and precursor to our notorious xenomorph, natch). I’ve never had much time for such criticisms, which seem to originate from a belief that fictional characters should be logically precise and bereft of human flaws like curiosity.

If those aspects of Prometheus bothered you, then you’re really going to hate Covenant. These guys venture onto a new planet without even a thought for helmets and seem perplexed by the idea of quarantine procedures. They are emotional, religious, curious, inconsistent – in short, human. In many respects, Covenant feels like a direct rebuff to those wanting flawless characters in their escapist entertainment. Without going too far into specifics, the film argues that perfection and humanity are fundamentally incompatible; we are weak, we are fragile, we are doomed by our curiosity, but surely within those imperfections our beauty lies.

That might give you the mistaken impression that Covenant is an optimistic film. It’s not. If Scott’s last film, The Martian, was the anti­-Alien, then this is the über-Alien. The Martian saw the potential of the human race to innovate and collaborate and create something wonderful together; Alien Covenant regards us as an infinitely fragile species hurtling through the expanse of space towards certain doom. In short, this isn’t exactly a crowd-pleaser.

Beyond recalling the brutality of the first film, Scott’s latest exploration of the Alien universe also revisits the perversity that made that film so distinctive. H.R. Giger’s design is grotesquely sexualised, like a distillation of the intermingled terror and excitement of our first exposure to sex. Covenant – eventually – probes these same orifices, exposing the viscous, lumpy corporeality of us. As we delve deeper into the truth of Covenant, uncovering its dark secrets, what we find is something akin to Cronenberg’s early films; a portrait of the fascinating failures of our physicality.

None of this to suggest that this is a flawless masterpiece, or even a film on par with sci-fi/horror classics like The Thing, The Fly or its 1977 predecessor. The screenplay’s ambition often twists into clumsiness – how many times does Billy Crudup need to remind us he’s a man of faith? – and its clinical approach makes it hard to empathise with its characters. The notable exception being Katherine Waterston, whose unabashed emotionality elevates her fairly stock characterisation. Michael Fassbender is excellent, too, though for entirely different reasons. Still, I’d forgive a hundred clumsy bits of writing for a blockbuster this distinctive, a franchise film with something to offer beyond healthy box office receipts.