Jeff VanderMeer’s deeply strange and brilliant new novel extends the meditation on the central question of non-human sentience in his earlier work. The alien intelligence that infected Area X in the Southern Reach trilogy was capable of such a profound biochemical mimicry that it shone a harsh light on the primitive nature of human cognition. Now, splicing together the DNAs of Godzilla and Frankenstein, VanderMeer gives us Borne.

In a world laid waste by a biotech company called, simply, “Company”, Mord, a massive flying bear more than five storeys high, is terrorising survivors. These include humans, mutants, animals and hybrid creatures which are revealed to be failed or aborted biotech experiments. Biotech spans a huge spectrum. Diagnostic beetles can enter a human system and heal illnesses and wounds. There are artificial living creatures such as feral children with wings and poisoned claws, and transgenic species that can morph from human to bear. Only three named humans inhabit this world. Our protagonist, Rachel, is a scavenger in the dangerous post-Company landscape. Her lover, Wick, is an ex-Company employee who makes biotech in his swimming pool laboratory. And “the Magician” is a shadowy creature who, it is rumoured, is collecting ammunition and soldiers to fight Mord and wrest control of the land from him. Then there are the “Mord proxies”, hundreds of smaller Mords who see the flying bear as their god and are impelled only by a ferocious bloodlust. Details slowly emerge of the kind of depredation wrought upon the world by the Company, along with a deliberately undersketched strand on the pre-Company world, disintegrating under unnamed political upheavals and wars that turn millions into refugees.

In one of her perilous salvaging missions, Rachel rescues from the furry depths of the sleeping Mord’s flank a creature “like a hybrid of sea anemone and squid: a sleek vase with rippling colours that strayed from purple toward deep blues and sea greens”. She brings it home and christens him Borne. Thus begins an unexpected relationship, often tinged with mother-child dynamics, that will carry most of the powerful emotional effect of the novel.

From the outset, Wick is suspicious of Borne and wants Rachel to give him up so that he can mine the creature for biotech. Rachel refuses, creating a fissure in their relationship that will have serious consequences. Borne, meanwhile, continues to grow, both physically and mentally, if that’s the right word for a creature that is neither human, nor animal, nor plant. He learns to speak, slowly at first, tripping over language in the way a human child does, and begins to absorb the knowledge and information Rachel feeds him as well as everything else that he can find on his own. Borne is a truly protean creature, able to turn himself into pretty much anything; he even puts out light, colour and smell effects which are sometimes delightful, sometimes unnerving. He can mimic his surroundings and other creatures. It turns out that human systems of knowledge are not the only things he absorbs; and, much later, in a frightening scene, Borne allows Rachel to see what his “sampling” of other creatures entails.

No one writes a post-apocalyptic landscape like VanderMeer, so detailed and strange in all its lineaments and topography

Everything changes after the Magician mounts a failed missile attack on Mord. In the aftermath, the attacks by the Mord proxies grow more frequent. There is a new urgency to the conflict between the Magician’s and Mord’s forces for control of the ruined city, and Rachel and Wick can no longer remain insulated from what escalates to a kind of civil war. There are thrilling, edge-of-the-seat set pieces of escapes and battles, including a final confrontation of almost cosmic proportions. All roads will lead to the ruined Company buildings, the origin and end of everything, the repository of all the horrors visited upon the city. The revelations here illuminate the nature of Wick, the Magician’s strategies, the history of Mord and Borne, even Rachel’s own past.

No one writes a post-apocalyptic landscape like VanderMeer, so detailed and strange in all its lineaments and topography, at once a wasteland and yet seething with the weirdest kind of flora, fauna and biotech, that last category manifesting yet again his abiding interest in the cross-pollination between the human and non-human. It may seem an odd connection to make, but VanderMeer’s recent work has been Ovidian in its underpinnings, exploring the radical transformation of life forms and the seams between them. The education of Borne coils around to become an education for his educators and, by extension, the readers – how do we understand non-human minds? Can we even ascribe processes of cognition to a creature such as Borne? In a heartbreaking scene of reckoning, Rachel realises that, to Borne, “on some level I’d never understand, there was no death, no dying, and in the end we stood on opposite sides of a vast gulf of incomprehension. Because what was a human being without death?”​

• Neel Mukherjee’s A State of Freedom will be published by Chatto in July. Borne is published by 4th Estate. To order a copy for £9.74 (RRP £12.99) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.