'Two possibilities exist," Arthur C Clarke once wrote: "Either we are alone in the universe or we are not. Both are equally terrifying."
In the cold urban wilderness of future Los Angeles, the former feels like the only conceivable answer - but that raises another, even eerier dilemma, which looms like storm clouds knotting in the sky overhead.
In a similar but distinct way to Ridley Scott's masterful original, Blade Runner 2049 mulls one of the meatiest questions around: is surface all that there is, or do life's currents run deeper than the things we can see, hear and touch?
Denis Villeneuve's film toys with both options, making neither a comfort - and in the process, maps out one of the most spectacular, provocative, profound and spiritually staggering blockbusters of our time.
Like its forerunner, everything about it says slow-burning art film, apart from its budget. Half a week after seeing it, I still can't quite believe it exists.
If you've encountered the trailers, forget them. Villeneuve's film isn't a wham-bam slab of save-the-world sci-fi - the Blade Runner world is and always was long past saveable - but a future-noir mystery about a missing child, and the existential crisis the case triggers in its investigating agent.
That's Ryan Gosling's Officer K, an LAPD sleuth whose beat, like Harrison Ford's Deckard three decades earlier, involves tracking down and "retiring" (executing) old replicants: bio-engineered androids who were manufactured as slaves, but got other ideas.
K himself - brilliantly played by Gosling in his magnetically inscrutable, Only God Forgives mode - is a new-model replicant, hard-wired for compliance. That makes things easier.
During a briefing on the missing-child case - which is prompted by a strange discovery K makes outside the cabin of a protein farmer (Dave Bautista) in the film's opening scenes - he speculates the moment of birth must be somehow connected to the formation of the human soul.
WATCH the trailer for Blade Runner 2049
"You've been getting on fine without one," shrugs his superior officer, Lieutenant Joshi (Robin Wright). And she's right. There's an efficiency to K's life that's icily beguiling, from his no-nonsense approach to work to his contented (if poky) home life with his romantic partner Joi (Ana de Armas), a mass-produced but customisable holographic AI who can flick between pretty '50s homemaker, kittenish intellectual, mini-skirted teeny bopper and more, in line with her lover's mood.
PALE FIRE
Even though their relationship is between an android and an app, it seems, for the most part, real - and this question, of whether human identity amounts to anything more than one algorithm brushing past countless others, is one to which Blade Runner 2049 persistently returns.
It's built into almost every line of the nimble, probing screenplay by Hampton Fancher (a co-writer on Blade Runner) and Michael Green (Alien: Covenant). In one sequence, K peruses two DNA sequences as if he's working with computer code, while back at the station he chants passages from Nabokov's Pale Fire as part of a rebooting ritual, which is enough to make anyone wonder where their brain ends and the great cosmic nothingness begins.
But it's also there in Roger Deakins's head-spinning cinematography - which, when it's not gliding over dust-blown deserts and teeming neon chasms, keeps finding ingenious ways to make faces and bodies overlap, blend and diffuse. Characters gaze at each other through glass screens and see the ghosts of themselves gazing back - just as some of K's actions seem to reflect Deckard's across the 30-year gap (his voice commands to a photography drone echo Deckard's to the Esper Machine in one of the original film's simplest but most memorable scenes).
Meanwhile, outside, the swarming streets are stalked by enormous, incorporeal dream-women, as if the animated geishas of the 2019-set original had climbed down from their billboards like giantesses descending a beanstalk.
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It's worth noting, and savouring, that Blade Runner 2049 isn't set in a newly forged dystopia, but the world of Blade Runner three decades on - almost, but not quite, real-time progress. The walls of elite citadels still glimmer with that strange and trembling water-light, while Pan Am, Atari and the Soviet Union are all still in rude health. As indeed is Deckard himself, who's now living as a hermit in the wreckage of Las Vegas, but who seems to hold a crucial puzzle piece in K's unfolding case.
It's an extraordinary part, extraordinarily played, and reminds you just how much more Harrison Ford can do than dog-eared charisma. A confrontation with Gosling in a forsaken Vegas concert hall, overlooked by flickering projections of Marilyn Monroe, Elvis Presley and Liberace, has a dazzlingly spooky thanatotic charge.
That Blade Runner 2049 is a more than worthy sequel to Scott's first film means it crosses the highest bar anyone could have reasonably set for it, and it distinguishes Villeneuve - who's masterminded all of this, somehow, since making Arrival - as the most exciting filmmaker working at his level today.
The film crackles with a thrilling finality: in the foyer afterwards, I felt like I'd just seen the last blockbuster ever made. But like Mad Max: Fury Road before it, it shows you just how much further this medium has to go. - The Daily Telegraph, London
• 'Blade Runner 2049' is on circuit.
