Ever since the publication of Horace Walpole's The Castle of Otranto, the gothic genre has been a forum for the return of the repressed. Its ruined castles, honeycombed with dungeons and secret passageways, are architectural models of the unconscious, and what dwells in them are the things we choose to be unconscious of: our blighted loves, our defiled virgins and deformed half brothers, our mad, our murdered, and their nagging, resentful ghosts. The problem inherent in the genre, however, is what happens when the stock of the repressed runs out. What can be left in the oubliette when movie stars swap spit with their siblings on prime-time TV and the ads during the Super Bowl broadcast feature horses farting in young girls' faces?

Patrick McGrath's method, developed in five novels that combine lusciously clammy writing with sly intelligence, has been to shift the gothic's focus from the repressed to the mechanisms of repression itself, from forbidden secrets to the ways his characters keep them. In Spider (1990) what matters isn't the protagonist's squalid family romance but the cairn of pathology he's piled on top of it. The condition in Dr. Haggard's Disease (1993) is nothing more exotic than lovesickness, but its symptoms include drug addiction and gender slippage. At the same time, McGrath knows which conventions of the genre to preserve. He sets most of his novels in the past, even if only the recent past, and in milieus picturesquely mottled with decay.

In Port Mungo, though, McGrath begins his narrative in the '50s; he then sets a great deal of it in the lofts and town houses of present-day Lower Manhattan, where a reclusive English painter named Jack Rathbone has come to launch his belated career and to forget some terrible things that happened when he was living in Port Mungo, a "once-prosperous river town now gone to seed, wilting and steaming among the mangrove swamps of the Gulf of Honduras." Chief among his misfortunes is that his older daughter, Peg, a fiery, half-feral sixteen-year-old, is dead, killed while riding through those swamps in a speedboat piloted by her drunken mother, Vera. At least this is Jack's version of eventsˇor rather, the version relayed by his sister Gin. In addition to being Jack's caretaker and number-one fan, she is the book's narrator, and between her possessive love, envy, spite, and sympathy, she's as unreliable as a Bush-administration spokesman. Ever since childhood Gin has stolidly tagged after her charismatic younger brother, warming herself by the bonfire of his personality. But at the age of seventeen Jack fell in love with the older artist Vera Savage and decamped with her for New York without so much as a "ta" for his sister.

New York in the '50s turns out to be too rich in distractionsˇalcoholic and carnalˇfor Jack's comfort, and the couple move south, first to Havana and then to Port Mungo, where Jack paints lurid, Gauguinesque canvases and Vera drinks and fucks around. In between fights and Vera's prolonged absences, they produce two daughters. Owing to those absences, Jack raises Peg mostly by himself. His child-rearing methods leave something to be desired: During a visit Gin watches him avidly suck a thorn from the girl's foot, then sterilize the wound by pissing on it. Peg grows up, grows apart from her father, then dies, and the mystery of her death becomes the thorn in the psyches of her survivors, the thing that drives Jack back to New York and heals his rift from Vera and then, twenty years later, causes their estranged daughter Anna to seek him out, setting into motion the novel's bloody denouement.

All of this is filtered through Gin's consciousness and narrative voice. The former is limited because she doesn't actually witness the novel's critical events and has to rely on Jack's or Vera's reports of them. The latter is at once perfervid, in the gothic tradition, and stodgyˇher sister-in-law aptly calls her a "pompous bitch." At times this makes for hard going. The descriptions of the city, especially, seem as thin as if they'd been cribbed from a guidebook (which is shocking, considering McGrath's status as the archetypal Englishman in New York), and one could do with fewer labored interpretations of the other characters' motives. Yet Gin is also a compelling mixture of intelligence, creepiness, and pathos. You can't tell if what she feels for Jack is hopeless yearning or suppressed fury and contempt. She's also someone who's lived vicariously for so long that you can imagine her killing through a surrogate.

Compared with Gin, the other characters are stereotypes, which makes sense when you realize that they are essentially her creations. But at times the obscuring mist that she throws up around them parts, and we get cryptic glimpses of what may be their actual, independent lives. Is Jack a genius or a narcissistic failure? Has Vera abandoned her family or simply tried to save herself? Was Peg her mother's victim or her father's? We can't say. All we have are intimations. For a gothic, Port Mungo seems like an overwhelmingly light book, suffused as it is by the glare of the tropics, but its enveloping, at times stultifying narrative voice is the equivalent of darkness. Figures emerge from it and then subside back into it. In between they act, and such is the character of that darkness that one knows how only later, by virtue of the wounds they leave behind.

This isn't McGrath's best bookˇfor my money, that honor goes to Dr. Haggard's Diseaseˇbut it may be his most ambitious.

Peter Trachtenberg is the author of 7 Tattoos: A Memoir in the Flesh and is currently at work on a book about suffering and its narratives.