There are certain things about Caleb Carr's new novel, The Angel of Darkness, that make me very cross. Page 169, for instance. The book has opened with the kidnapping of a 14-month-old girl. Carr's heroes have just visited the house where they know she is being held by a nurse with a record for smothering babies. Unable to gain access, they repair to the Cafe Lafayette, "in order to digest some lunch along with our exploits". Rule one of creating empathetic characters: do not have them slurping oysters when a child's life is in danger.

The fate of this baby bothered me far more than the more graphic descriptions of mutilations which coloured his first movel. Set in turn-of-the-century New York, The Alienist is a horribly compulsive tale about a killer of boy prostitutes whose favourite trick is to remove his victims' eyes and keep them in a jar. The authorities refuse to admit that the murderer even exists. It is left to psychiatrist - or alienist - Doctor Laszlo Kriezler to track him down.

Kriezler also appears in The Angel of Darkness but in both novels he remains an elusive character - the two works are narrated by different members of his detecting circle, a clever device for producing sequential books which still have individual life and form. Carr is a clever man, and despite the fact that he left me boiling with frustration for over six hundred pages, an immensely likeable one; smart, articulate and anxious to be helpful.

He is in London, briefly, before jetting up to Edinburgh. It's what happens when you issue the follow-up to a runaway bestseller. (The Alienist was published in 1995 and stayed in the New York Times bestseller list for 25 weeks). "It goes with the territory," he says easily. He recently got an ex-directory phone number. "Somebody called me up at 4am from California, some weird person, obviously on drugs, demanding to know how I'd gotten famous, how he could get famous... at that moment I thought, 'Okay that's it'."

The subject matter of his novels must make such moments somewhat chilling, but Carr is able to detach from the more lurid side of his books without difficulty. He is, in essence, a 19th-century novelist, writing big fat naturalistic narratives. "I think it's the writer's job to entertain, and to educate. If you try to go too far in either direction, that's when you get into trouble." He is scathing about the current vogue for confessional books: "I think that's cheating. I think you must universalise your experience."

Carr could sell such a memoir with ease. His father was Lucien Carr, a journalist who introduced Jack Kerouac, Allen Ginsberg and Williams Burroughs. Lucien achieved fame of his own when he stabbed dead one of the group's hangers-on. (He spent two years in prison as a result.)

The Beats would regularly drink themselves beneath the Carrs' kitchen table. "I liked Kerouac very much," says Caleb Carr. "He was the only one who knew how to be nice to children. Allen [Ginsberg] was very nice as well, but he had a terrible - illegal - taste for young boys. Children can smell danger, particularly children from New York. We knew that there was something about Uncle Allen that wasn't quite right."

Carr politely declines to go into detail about the nature of his relationship with his father other than to say, with uncharacteristic lack of directness: "My knowledge of the violence done to children is not secondhand."

His alter ego, Laszlo Kriezler, would have no trouble in deducing that this must be at the heart of his apparent casualness when it comes to writing novels about the dreadful things adults can do to their young charges. "Because of my own life, I don't have trouble facing the terrors that children go through."

After a troubled educational history, Carr wrote a coming-of-age novel called Casing the Promised Land which was published and sank without trace in 1979. He devised a cunning plot to persuade his publishers to accept his idea for The Alienist. One of the characters in the book is Theodore Roosevelt, who was a Commissioner for the New York police before going on to become President of the United States. Carr put together the proposal as if it was a history book, even doctoring a photograph of Roosevelt to make him appear next to a man that Carr claimed was Laszlo Kriezler. (In fact, it was the composer Grieg). "I concocted 20 pages of shameless lies." Great story, the publisher said - and only then did Carr confess that he had made it all up.

Such planning is typical of the way Carr has approached his career. He plots his books meticulously - using up whole walls of his New York apartment to sketch them out. He researches for a full nine months.

Such diligence leaves little time for much else. He lived with a woman once, "for one week", and then she left him. He split up with his current girlfriend a week before he flew over here. The way he discusses women can sound dismissive, but it's more political naivety than malice. He talks openly on many topics in the way that very intelligent people often do, pausing to correct himself if he has not chosen exactly the right word to explain what he means.

He is particularly scathing of Scott Rudin, the producer who bought the screen rights to The Alienist. One of the many stumbling blocks in getting the film made has been Carr's refusal to turn the one woman in Kriezler's group, a character called Sara Howard, into the love interest.

"All you need in Hollywood is a concept, a star and a release date," he scoffs. "Then a few months down the line they think, 'Oh, the script'." It is this lack of self-protective discretion that wins me over to Carr. In the end, his ambitions are endearingly old-fashioned. "I don't care whether the film gets made or not. The novels have a life of their own. I just want to write good ripping yarns, good stories."

'The Angel of Darkness' (Little Brown pounds 15.99) is published today.