Peter and Rebecca Harris are an affluent couple settling into what promises to be a comfortable Manhattan middle age. The opening pages of Michael Cunningham’s new novel suggest that insofar as marital happiness is possible, the Harris’ have found it: not an impossible perfection, but an agreeable arrangement in which each tolerates the other’s harmless flirtations.

They are shaken out of this complacency by the arrival of Ethan, or “Mizzy”, Rebecca’s much-younger brother. Beguilingly handsome, Mizzy soon leads Peter to question the very foundations of his character. At the heart of the book is an encounter that leads Peter to ask himself: “How can Mizzy, alone among the realm of men, excite him so? Is it possible to be gay for one man only?” Cunningham’s elegant prose is pitched midway between the cold exactitude of Coetzee and the more languid pleasures of Alan Hollinghurst. Like Hollinghurst’s The Line of Beauty, this novel is a virtuoso performance of visual observation. But where Hollinghurst specialised in architecture, Cunningham revels in the emancipatory power of modern art.

In its evocation of the ability of a single individual to unhinge a stable environment and its deft satire of New York society, By Nightfall is startlingly reminiscent of Edith Wharton’s The Age of Innocence. Like Wharton’s Newland Archer, Peter Harris is engagingly imperfect. As Harris himself muses, "We don’t care about Emma Bovary or Anne Karenina or Raskolnikov because they’re good…[but] because they’re not admirable, because they’re us, and because great writers have forgiven them for it."