“You’ve no need to invent anything. Your life and character, the way you look at the world should be your only material,” says the woman referred to as “L” in Delphine de Vigan’s captivating novel, Based on a True Story (beautifully translated from the original French by George Miller).

L is offering advice to the narrator, a writer named Delphine: “You’ve proved to them that you know how to do something different, that you could take hold of reality, have it out with it. They’ve understood that you were looking for a different reality and that you were no longer afraid.” When Based on a True Story opens, Delphine is teetering on the edge of collapse. Her previous book – a fictionalised account of her mother’s suicide (also the subject of de Vigan’s previous book, Nothing Holds Back the Night) – won her haters inside her family, but fans outside: “I hadn’t imagined readers feeling moved or fearful. I hadn’t imagined that some would cry in front of me, nor how hard it would be for me not to cry with them,” she says.

In the midst of this emotional exhaustion, she meets L at a party. L is an alluring prospect from the start, the kind of woman Delphine tells us she isn’t – “impeccable, with her smooth hair and perfectly filed vermilion nails that seemed to gleam in the dark” – and the two women strike up a friendship. It’s oddly one-sided, though. Delphine becomes increasingly dependent on L, something that the latter, who apparently begins to dress like her new friend, encourages, but all the while she herself remains slightly aloof and unknowable. So far, so Single White Female – “At times, her silhouette stood out like a video projection of my own body on a softer, smoother surface” – an underlying sense of dread and terror spun out of everyday kindnesses and coincidences.

The tension builds, peppered by reminders of Delphine’s “complicity” in her fate. But the fact that de Vigan takes her epigraph from Stephen King’s Misery – the story of a writer who’s kidnapped by a crazed fan and forced to rewrite the plot of his latest book to her liking – is clue enough that the heart of the story lies in the complicated relationship between writer and reader. It’s working out who’s who that’s the mystery. Delphine wants to return to writing fiction, but L, who’s a ghostwriter by trade, strongly suggests she continues to take real life as her subject, arguing that Delphine’s audience wants “authenticity” – whatever that is.

All writing is constructed on shifting sands, but I’ve never read a book that makes the complex relationship between reality and fiction both as visible, and at the same time so opaque, as here. I was captivated. Combining the allure of Gone Girl with the sophistication of literary fiction, Based on a True Story is a creepy but unapologetically clever psychological thriller that also aces the Bechdel test (at least two women in a work of fiction, talking to each other about something other than a man).