The Master by Colm Tóibín

"Why can't gay writers give gay men happy endings, as Jane Austen gave heterosexuals?" Colm Tóibín asked in Love in a Dark Time. One absentee from that study of gay writers was Henry James (though, for some, the nature of James's sexuality remains vexed). Tóibín has subsequently written on James, focusing on his Irish blood. His interest in "the Master" now resurfaces in his fifth novel, the first since the Booker-shortlisted The Blackwater Lightship in 1999.

If today's gay novels can sustain happy endings, Tóibín's own have not followed his prescription. One motive for writing Love in a Dark Time was, he confessed, an "abiding fascination with sadness... and, indeed, tragedy". The opening pages of The Master underline how logical his choice of subject therefore is. The 52-year- old James is experiencing a "wearying, gnawing sadness" as he looks forward to the opening of his play Guy Domville. It must compete with the gaudy successes of the Irish prodigy, Oscar Wilde. Throughout rehearsals, James is haunted by a fear "that worldly glamour and universal praise would never be offered to him". Sure enough, he suffers terribly on the first night.

After passing the evening enduring Wilde's "crude and clumsy" An Ideal Husband, James returned to witness catcalls and abuse greeting his own piece. Still worse, he initially mistook the cacophony for acclaim. Disgrace at the play's failure is described rather like sexual shame: "Now he would walk home and keep his head down like a man who has committed a crime and is in imminent danger of apprehension."

The experience foreshadows Wilde's very different fall, from which James held himself conspicuously aloof. Here, Edmund Gosse regularly imparts the latest news. Far from empathising with Wilde, Tóibín's James responds with flippant platitudes. He will deploy a similar strategy later, confronting domestic travails in Rye. Especially vivid - and hugely entertaining - is James's dismissal of his drunken household staff.

Gosse warns James of a wider climate of reproach accompanying the pursuit of Wilde. He poignantly poses - or almost poses - the key question on James's sexual nature: "'I wondered if you, if perhaps...' 'No,' Henry turned sharply. 'You do not wonder. There is nothing to wonder about.'"

As always in Tóibín, a tension between public and private selves - between desire and imposed conduct - informs the most poignant scenes. He attributes to James a deep wish for sexual expression rather like that privately admitted by E M Forster. The Master documents the ebbing of a younger, more openly sensual James, overshadowed by the older nostalgic. There are long episodes of recall: the moment with "Paul" when James came nearest to sex; a sleepless chaste night spent, aged 22, in bed with Oliver Wendell Holmes.

Most memorable is what Tóibín takes from the uncanny relationships that the older James initiated with striking young men. Of four candidates - Hendrik Andersen, Jocelyn Persse, Howard Sturgis and Hugh Walpole - Tóibín selects Andersen, the first such beloved and the most diverting. This absurdly beautiful Norwegian sculptor, resident in Rome, responds to James's cluckish wooing with a mercurial blend of naivety and guile.

For a time this quite unbalances the writer, as when he listens forlornly to Andersen undressing in the guest room at Rye. Andersen is deaf to James's acute comments on his absurd plans for a "world city" that will be filled with his own hyperbolic statuary. James proves equally blind to the folly of the affiliation.

This is a taut, well-crafted, mesmerising novel. As with most historical fiction, there is the odd moment of uncertain period phrasing and the possibility that Tóibín's empathy with his subject risks his own concerns bleeding through too directly. Ultimately, however, his limpid, measured prose illuminates this fictional James superbly. The Master is a masterly achievement.

Richard Canning is writing a biography of Ronald Firbank