A writer makes things up. In making things up, a greater truth is revealed. This is the premise of much fiction that nostalgically grasps for a certainty that feels as modern as taxidermy. “You couldn’t make it up,” is the hackneyed vernacular.

Right now: governance via tweets, poisonings in Salisbury, ice shelves dissolving, the anniversary of a flammable tower block turning into a tomb. Jacob Rees-Mogg being spoken of as a viable prime minister. Nazis in Charlottesville and Hungary. Steve Bannon. Trump meeting the two Kims: Kardashian and Jong-un.

Last summer, Olivia Laing wrote Crudo in “real time”, whatever that might mean in the perpetual present of accelerated social media. Laing is a mesmerising critic and memoirist, a travel writer in that she connects the inner to the outer world. She is simply one of our most exciting writers, who has explored through her work loneliness, alcoholism and art in The Lonely City and The Trip to Echo Spring. Every tangent is a tributary for Laing that leads somewhere unexpected. She wanders both as insider and outsider, queer, curious, unsettled, erudite, wondering what it is to be an artist.

Crudo is her first novel. About what she did last summer. She got married, she had a luxurious holiday in Italy. She settled down. Only she isn’t Laing. She is the late American writer Kathy Acker. Or she writes as Kathy. As if Kathy were still alive and she hadn’t died a long time ago from cancer that she was in denial about.

Acker, the arch curator of her own myth, wrote as others too. She wrote as Dickens. Or Cervantes. She would be Don Quixote. She would be whoever she said she was. One book was called My Death My Life by Pier Paolo Pasolini. She wrote out of torment, out of altered states of pain and sex. Everyone wanted to have sex with her but no one wanted to stay with her. She was a nomad. She wanted to blow apart the idea of authorship. She wanted no other woman to be like her. She would be radically alone, a one-woman show in the male-only avant garde.

Laing reads Chris Kraus’s biography of Acker and decides to inhabit Acker. What is a persona after all? Laing said in her review of Kraus’s book that Kathy was “inimitable”. We all know that Kathy lied, though. Can you impersonate someone who faked for some kind of living?

Who cares? Laing can blur the edges. She can embody Kathy. It gives her freedom to move – Kathy’s gift, after all. So here they are: Laing/Acker in the summer of 2017, unsure if they can commit. To one person. To one place. Though she is on a sunlounger eating gorgeous food, the world feels like it is turning on its axis, like it might end quite soon. Korea and Grenfell. Ecological disaster, Libyan coastguards shooting at refugees. A woman liveblogs her rape on Instagram.

The luxury pools beckon and yet the sins of the world are inescapable, the anxiety of just trying to be human. Kathy is no longer alone, but caught up.

Sometimes, Kathy Acker is very present and masterfully referenced – the hatred of her breasts, the STDs, the live sex show, her mother’s suicide, the poor little rich girl, the creator of herself. Sometimes, it is Laing who is more present as we know her from her work, and sometimes it doesn’t matter at all who is talking, because Crudo seduces from the first sentence. Laing as Acker is not a literary device – it is literary detonation. Everything accelerates from there.

Gordon Burn did this with the summer of 2007 in Born Yesterday: The News As a Novel . The fragments of the McCann case, floods, the assault in Glasgow airport, Damien Hirst’s $50m diamond-encrusted skull gave us a snapshot of how news shatters. Is it ever whole?

Laing’s prose shimmers and is selfish then, suddenly, full of love. It’s a high-wire act. This is the novel as a love letter to Acker. She gives her a happier ending than the one she had. She asks us what a novel can do when unreality rules. She asks what it is like to be alive when the old order is dying.

Acker famously wrote out of torment, hurt, sex. Laing fears contentment, hardly a radical state. Maybe. “I was beginning to think that drinking might be a way of disappearing from the world,” she wrote in another book. Here she asks how we might not disappear. Energy shimmers. Kathy marries. In spite of doubt. And death. She reaches out for something extraordinary. Crudo is a hot, hot book. The fuse is lit.

• Crudo by Olivia Laing is published by Picador (£12.99). To order a copy for £11.04 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99