Fantasies of walking out of one’s life are always alluring, not least because in reality, they seem at once improbably unrealistic, somewhat shamefully naive and, at bottom, terrifying. We nurture these ideas of stepping out of ourselves in private, aware that they also suggest a certain narcissism; and that they are usually available to those who can choose displacement rather than have it thrust upon them.

For Dylan, the 38-year-old Englishwoman who calls time on the New York existence she has built for herself by abruptly quitting her job in advertising, subletting her apartment and seizing on a three-month shift as a house-sitter, the fantasy appears to pay almost immediate dividends, at least symbolically. She wants to become a writer; the apartment she moves to is in Alphabet City. Her relationship with her West Coast boyfriend is bloodless to the point of anaemia; enter, via the fire escape, a handsome and charismatic man in a state of near-perpetual sexual readiness. Even the cat she has promised to feed in return for free bed and board is undemanding. A new life awaits.

But Miranda Pountney’s impressive debut novel is a far darker affair than this romp-inflected precis might imply, and certainly has more in common with Sylvia Plath than Sarah-Jessica Parker. Its mode is volatility, as Dylan’s fragmenting interior life collides with spiky social set pieces, including a gruesome birthday weekend in the Hamptons that ends with a mildly dislikable character slicing her hand open on a wine glass, one presumes to effect an escape. Meanwhile, Dylan’s affair with the married Gabe has the reader silently mouthing warnings that they know will go unheeded, and worrying in turn about the unwritten manuscript, the absent cat and a clock that appears to be ticking on accommodation, creativity and, as Dylan’s friends keep reminding her, fertility. It is a book founded on the anxiety that undermines our drive towards attachment and stability, and it thrives on a constant sense of slippage and precarity, a jumpy exploration of what it might feel like to cede control, and what might take its place.

• How to Be Somebody Else by Miranda Pountney is published by Jonathan Cape (£16.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply