It's a pleasant spring evening on Broadway. The last stragglers from a service at Grace Church are still chatting on the pavement outside; across the way, the worshippers of Mammon are gazing, enraptured, into store windows still brightly illuminated for late-night Thursday shopping. But as night falls on New York, a serial killer is about his brutal business. Somebody is murdering child prostitutes - boys who dress as girls for the titillation of their clients - and mutilating their bodies. Respectable society doesn't want to know: the prostitutes themselves, tanked up on drugs and terrorised by pimps, are hopelessly vulnerable.
Sounds like just another tale of everyday life in New York, doesn't it? And, in a way, it is - except that it took place 100 years ago. Caleb Carr's novels, The Alienist (1994) and the newly published The Angel Of Darkness, set in the late 1890s, paint a picture of old New York that manages to be both reassuringly historical and shockingly contemporary; and Carr, a historian by training and inclination, makes no apology for that.
"Part of the reason for writing these books," he says, "was that I got so tired of people saying that New York in the old days was so wonderful and charming. New York has been a horrible, slime-infested place ever since the Dutch founded it and I wanted people to understand that it has always been a very rough city - that, 100 years ago, drug abuse and police corruption were just as much issues as they are now.
"But Americans are always fascinated by New York, in the same way that Americans are always fascinated by crime; and I think that has to do with Americans being so hypocritical about sin. We're fascinated by it at the same time as we pretend we're really above it - I mean, look what's going on now, this ridiculousness in Washington - and I think New York symbolises all of that for America. Most Americans profess to hate New York and say it's a den of sin and everything - yet they're the very people who, when they come to conventions in New York, act like absolutely degenerate swine."
Carr's extraordinarily vivid picture of turn-of-the century New York is a product of long hours spent both on the streets of the city and in libraries. He grew up in the places he now writes about, and his narratives move easily through a variety of urban landscapes from snooty to seedy; his storylines, meanwhile, meander along like a river, flowing lazily over a bed crammed with bits and pieces of historically accurate information and, occasionally, real-life characters, such as the president of the Board of Commissioners of New York City's Police Department, one Theodore Roosevelt.
These big, leisurely books may weigh in at more than 600 pages in paperback and deal with a time when life in Manhattan - and everywhere else - moved at a considerably slower pace, but they're as gripping as any hardboiled contemporary crime thriller, as the sales figures will confirm. The Alienist became a best-seller within a month of publication in 1994 and The Angel Of Darkness bounced on to the New York Times best-seller list at Number Four when it came out in the US last autumn.
Carr regards this commercial success with a kind of bemused scepticism. "It's just pure, dumb luck that these books have plugged into a certain mentality right now - who knows if it's an end-of-the-century thing, or something to do with the drugs-and-crime culture. I could have done this 10 years ago, or 10 years from now, and nobody would have read them," he says.
One thing is for sure: nobody would have read them at all if he hadn't lied to Random House about The Alienist in the first place. "I brought them a 20-page proposal which had quotes and sources and the doctor's photograph and I told them it was a true story and they accepted it on that basis." When they discovered it was fiction, he says, they were appalled. "They said, 'we don't know how to sell this - what is it?' And they absolutely hated the title. They said people would think it was either science fiction, or about immigrants. If anything is gonna destroy modern civilisation," he concludes grimly, "it's sales and marketing."
The "alienist" in question is, in fact, a psychologist, Dr Laszlo Kreisler, and both books revolve around his efforts to solve a series of particularly horrifying murders by the application of the technique we now know as psychological profiling. Kreisler is aided and abetted by an enthusiastic and somewhat eclectic group of characters: his driver, a former criminal; his bodyguard, a convicted murderer who also happens to be very large and very black; his friend who works (though not, it must be said, often) as a journalist on the New York Times; a pair of Jewish detectives, the Isaacson brothers; and Roosevelt's former secretary, the feisty Sara Howard.
Much of the appeal of The Alienist and The Angel Of Darkness is derived from the shifting relationships between the members of this motley crew, and the variety of characters has also provided Carr with a neat fictional device; the ability to tell each story from a different point of view. The Alienist is narrated by the slightly stuffy journalist, John Schuyler Moore; the voice in The Angel Of Darkness belongs to cheeky-chappie driver, Stevie Taggert; the next book in the series, says Carr, will, in all likelihood, be Sara's story.
"Each of the characters is a piece of me," he explains. "Stevie, for instance, is a very big piece of me. But they're all voices that I talk in sometimes, anyway - aloud. My neighbours think I'm nuts." He admits to having doubts about writing from the points of view of Sara, a woman, and Cyrus, a black man - there's a certain amount of presumption involved and it is very daunting" - and as to whether the enigmatic Dr Kreisler will ever get to tell his own story, well, even Carr says he doesn't know that yet. As long as people are happy to read his "alienist" books, he says, he's happy to go on writing them. But he has an idea for another sort of book altogether, which he describes as "a futuristic historical novel". Back to the future, you might say; and if it's even half as entertaining as the others, it'll be back to the best-seller list for Caleb Carr.
The Alienist and The Angel Of Darkness are published by Warner Books and Little, Brown at ú5.99 and ú9.99 in the UK.
