Crooked timbers of humanity

Patrick McGrath, demon king of New Gothic fiction, cares more about compassion than creepiness

The first thing that interviews with Patrick McGrath will always tell you is that the novelist grew up outside the gates of Broadmoor special hospital, where his Glasgow Irish father was a much-loved and reforming medical superintendent. He enjoyed "a happy Berkshire childhood" in the far-from-sinister shadow of "one of the finest flowers of progressive Victorian thinking". "Well-stabilised" patients who worked on the estate would meet "the boss's kid" on social occasions. "There was nothing I ever remember as a manifestation of insanity in my childhood."

The first thing that interviews with Patrick McGrath will always tell you is that the novelist grew up outside the gates of Broadmoor special hospital, where his Glasgow Irish father was a much-loved and reforming medical superintendent. He enjoyed "a happy Berkshire childhood" in the far-from-sinister shadow of "one of the finest flowers of progressive Victorian thinking". "Well-stabilised" patients who worked on the estate would meet "the boss's kid" on social occasions. "There was nothing I ever remember as a manifestation of insanity in my childhood."

That came later, in his art: a mesmerising suite of novels that explore, in hallucinatory neo-Gothic prose, the hidden stories of terror, obsession and sudden violence that the happy child never knew. It's hard to think of any other body of work in current British fiction that boasts such a pungent, lingering flavour. His new work Martha Peake (Viking, £12.99), piggy-backs a "romantic adventure" of the American Revolution on top of a festering late-18th century tale of madness, monstrosity and medical malpractice, stamped with all the dark McGrath hallmarks. Nor does he plan any drastic change of weather for his books: "The imperious doctor or scientist; the naive young man; sanity, evil and enclosure; the abuse of social power, particularly at the hands of the medical profession... I'd imagine that these themes will recur." Thank Beelzebub for that.

McGrath spends his winters in Manhattan, where he nabbed a loft in TriBeCa in 1981. For half the year, however, he lives - well, where would you imagine? Opposite Bedlam. It's a dainty Regency house, once occupied by clergy from Southwark Cathedral, across the road from the Imperial War Museum - site of the first Bethlehem Hospital.

This location belongs to the realms of you-couldn't-make-it-up coincidence. For the house belonged to his wife, the actress and screenwriter Maria Aitken, whom he married in 1991 after a high-velocity courtship that comes straight out of the pages of a much frothier novelist than this one. Introduced at a New York dinner party, the couple married seven weeks later, in the shotgun-wedding nirvana of Reno, Nevada. (His stepchildren include Jack Davenport, star of This Life and dedicatee of the wonderful Asylum.) In a San Francisco airport bar, they devised their vows on a napkin. "We had an hour or so to kill, and we figured we ought to get some vows together, rather than just take what was on offer in Reno." It beats any Amy Jenkins plot.

The unquiet ghosts of Bedlam at our back, we talk in the pretty circular garden, with the chimes of Big Ben sounding faintly in the distance. In person, McGrath resembles not so much the cutting-edge Manhattan novelist he is as a benevolent and slightly shambling GP. Given his father's achievements, did he and his three siblings feel any parental prod towards the family trade? No; Patrick senior "would have been delighted" if it had happened, but the pacific healer was merely "very anxious that none of us join the army".

McGrath junior studied English in Birmingham. Then, adrift in the usual post-graduation haze, he took up an offer from one of his father's colleagues and worked as a social assistant at an asylum in northern Ontario. "Grim beyond belief", this penitential blockhouse made dear old Broadmoor look like a country hotel. He stayed three years, moved west to teach in Vancouver, then hid himself away on Queen Charlotte Island to write fiction. "I had a sort of Malcolm Lowry idea of building a shack, settling in and being absolutely undistracted."

It was," he recalls, "a long apprenticeship", but it led in time to one of the gamiest, most addictive styles in modern English prose. In 1981, he left this fastness for Manhattan: "a cherchez la femme story", as his artist girlfriend insisted on the shift. He loved it there, and plunged into the feverish creative mood of the Lower East Side, where ambition was "accepted, encouraged and rewarded". He co-founded a shoestring literary magazine and distributed it using "the sort of envelope in which drugs were sold on the street corners".

This was the high noon of postmodernism, when "a fierce interest in matters Freudian" converged with "the collapse of the distinction between high and low culture" - and a new respect for genre fiction. It's curious to reflect that McGrath's incomparable evocations of passion and perdition in "a rather grainy Forties England" - where the cast of Brief Encounter find themselves on a Hammer Horror set - owe so much to the terminal cool of Andy Warhol's Greenwich Village.

A story collection appeared in 1988 and a novel, The Grotesque, in 1989. Did his dad approve? Eventually. But when Dr McGrath read an early story, "He snorted and said, 'Derivative'. 'Derivative of what?' 'Joyce'. It hadn't occurred to me. I said, 'Well, if you'd been sober when you read it, perhaps you wouldn't be so dismissive.' He came back quickly: 'If you'd been sober when you'd written it, I wouldn't need to be.' "

Things improved. Dr McGrath helped to get the clinical details of schizophrenia right for his son's creepily unsettling second novel, Spider. Then the wise and kind physician was consulted on the creation of a mad and cruel one in Dr Haggard's Disease, dedicated with "love and gratitude" to him.

The figure of an - ostensibly - sadistic surgeon broods over much of Martha Peake. Young Ambrose, the fanciful narrator, visits chilly Drogo Hall to hear from his uncle the tale of the Cornish smuggler, Harry Peake. His body wrecked in an accident that kills his wife, this tortured titan expiates his guilt by showing off his weird, ridged back in London taverns. Treated as a grotesque freak, Harry "embraces the monster" and acts as one - a classic McGrath motif. The coldly empirical anatomist, Sir Francis Drogo, takes a more than clinical interest in him. Meanwhile, Harry's daughter Martha escapes the deforming love of her father. She becomes an - ambiguous - heroine among the New England patriots.

McGrath conjures up the fetid lanes of London and rugged coasts (and colonists) of Massachusetts with an exhilarating virtuosity. The mangled Harry, meanwhile, comes to symbolise the new state labouring to its bloody birth: "He's a great protean mixture of larger-than-life attributes. I wanted this towering figure to suggest America."

As for Ambrose, who tells the tale, we gradually learn not to trust his every word. With McGrath, the seductive yarns of an unreliable narrator often whisk us into a fog of doubt. There we learn to read, as Ambrose does with his wily uncle's tale, "against the bias" of the teller. McGrath strives to make sure that "there has been enough pleasure on the journey, and enough clues laid down, so that when the 'Ah-ha!' moment comes, you realise that you've had all the information but you haven't organised it."

The pleasure of the journey is immense. And so is the pathos: we embrace the giant suffering of Harry, for all the "crooked timber" of his spine - and of his grief-twisted deeds. It was in the period of the novel's setting that Immanuel Kant famously wrote: "Out of the crooked timber of humanity, no straight thing can ever be made."

Yet, two centuries on, the ostracised "monster" still serves as a handy scapegoat. McGrath comments that "I'd have thought we have regressed in terms of understanding and tolerance of the deviant. These recent events in Portsmouth show that the mob is just beneath the skin of the community." His own work shows us how to separate the afflicted person from the barbaric act - just as his late father's did. Enlightened Broadmoor (if not brutal Bedlam) still casts its enduring shadow.