Life finds a way, or so the saying goes. What if it found a different one? What if dinosaurs still ruled the world, or insects, or giant cats? What if doors between parallel realities began to open? Would you slam them closed or try to cross those thresholds?

I have a weird relationship with Adrian Tchaikovsky. I think he’s a lovely chap with a gift for writing really goods book I’m really uncomfortable reading. Dogs of War was brilliant, but milSF. Children of Time is a modern classic, but spiders. Walking to Aldebaran was a genius idea, but grim and sort of viscerally sticky. Consequently, I don’t tend to request his books as there’s only so many times I can think “this is really good but not my cup of tea” without feeling guilty; I usually leave them to reviewers who will love them wholeheartedly.

Nonetheless, I accepted The Doors of Eden under the confused impression that it was Adrian Tchaikovsky trying his hand at portal fantasy. Well that’s different, I thought, colour me curious to see what he does with that. You get to laugh at me now, it’s okay. For the avoidance of doubt, The Doors of Eden is not portal fantasy, although I guess I could call it portal scifi. And I have zero regrets about requesting it, because it’s my first foray into Tchaikovsky’s work that I’ve unabashedly enjoyed.

Let’s start with the lovable cast: Lee, gentle but stubborn, a cryptid hunter who has never got over the death of her girlfriend. Mal – the girlfriend – fierce, daring, incapable of passing up a pun (SUCH PUNS); crucially, not actually dead. Dr Kay Amal Khan, hiding vulnerability under a flamboyantly confrontational attitude. Spymaster Julian Sabreur, as conventional as he is loyal, floundering in self-deception. Alison the brilliant MI5 analyst, unflappable in the face of the inexplicable. Stig, an endearing mix of pragmatism and lyrical philosophy, so resigned to the terrible things he knows are coming his way. They are an absolute delight. The only ones I didn’t click with were antagonists, whose POV often felt oddly like padding.

You could be excused for thinking the Interludes that cross-cut the emerging conspiracy thriller narrative are padding too, but you’d be wrong. It’s as if David Attenborough stopped by to interrupt the action for a quick chat about evolutionary roads untravelled, and they’re glorious. This is arguably what Tchaikovsky always does best, of course: centring the non-human, in this case exploring possibilities that could have resulted in a different organism dominating the planet.

Thankfully, there are no spiders. Instead, we meet the practically immortal space-faring trilobites; the genocidally ferocious sea scorpions; the intensely hierarchical rat/weasels; the socially liberal do-gooding communist Neanderthals. And then it becomes clear: these are not mere possibilities or thought experiments. Every path was taken, parallel realities branching out from a shared past – and now speeding towards a single future as the multiverse begins to collapse in on itself. As realities begin colliding, alien intelligences reach through newly-opened doors to make contact.

Back in the London we recognise, Alison has no rational explanation for the weird leads that sometimes appear on her screen, even when it’s turned off. Julian wouldn’t believe it, although he turns a blind eye if the intel helps him safeguard Queen and country. Dr Khan might be able to explain it, but she’s keeping a low profile to avoid transphobic nationalists.

Mal disappeared one night on Bodmin Moor, leaving Lee guilty and haunted. Now Mal’s back to snatch Dr Khan and save the world – all the versions of the world – with a thickset operative from a parallel reality. But after four years in another dimension, she’d dearly like a cuppa first.

“It’s a million to-one long shot, and only these two desperate lesbians can save the world“

The Doors of Eden is an extravagant act of imagination, gloriously compelling in its broad strokes if somewhat baggy in the middle. On the plus side, it unashamedly takes its time to establish characters and relationships; but there were moments where I found myself wishing it would get to the point.

This may have been an artefact of the intentionally uneven pacing. The Interludes inevitably bleed tension from the narrative, but there are also a series of false summits before the peak (the scene at the Natural History Museum could be an explosive finale; here, it’s just the end of Act One). The climax itself eschews action: instead, people stand around and talk a lot, mostly about how all this is far too complicated to understand.

They’re not kidding.

Tchaikovsky’s victory is that for all the complexity, I never felt lost or overwhelmed by biology or mathematics. When the final set of branching possibilities played out, it felt vastly appropriate – a figurative Choose Your Own Adventure, fingers stuck in every decision point to try and avoid disaster. I sort of wish the ending had been left ambiguous – giving the reader the option to choose our preferred reality, if you will – but I’m equally grateful to have been given closure (and it does make more sense in context).

At its heart, The Doors of Eden is a parable of borders and community; and a celebration of finding common ground no matter how insurmountable our apparent differences (you try communicating with a trilobite). Those interested in saving the multiverse wish to do so because it’s right and are prepared to sacrifice themselves for the greater good. They are defined by their compassion, their curiosity and their commitment.

“We are going to mend the universe, if it can be mended. Or we will watch it die, because someone should.”

The antagonists are interested only in saving their bit of the multiverse, and screw the rest. Their focus is on keeping the Other out; they rely on lies, fear and violence to preserve a way of life that benefits only themselves. It’s no coincidence that our protagonists are primarily marginalised women (lesbian, trans, women of colour).

While I’m always here for big-hearted, optimistic science fiction, it did feel a little unsubtle, largely because of how transparently awful the villains were. And yet… maybe my real problem is that they’re far too believable, and in 2020 I guess I need a little more optimism rather than a mirror for the self-perpetuating power structures of the real world. But before I descend into too much navel-gazing, let’s be very clear: my name is Anna, and I enjoyed an Adrian Tchaikovsky novel.

Which is brilliant news, because I have 3 more unread on my shelf.

Content warning: transphobia, deliberate misgendering (as a marker of villainy)

I received a free copy from the publisher in exchange for an honest review.

The Doors of Eden is available now in the UK.