The narrator of Scott Spencer's new comic novel about a high-end sex tour finds it curious that he never sees the image of the tour operator, Lincoln Castle, reflected in an airport window or an elevator security mirror.

Avery Jankowsky, a young freelance writer, realizes that under the bed of prostitution some kind of vampire lurks. But then again, lives are messy, sex happens, and almost every intimate entanglement involves unstated barter or purchase. Who's to say what's right or wrong?

		"WILLING" By Scott Spencer Ecco ($24.95)

"Willing" conjures up this ambiguity with a flourish. Attuned to the small, surprising details of the lighter side of sin, Spencer has fashioned a novel that is not only whipsmart and thoughtful, but funny enough to make you snort your coffee out your nose.

The prostitution in "Willing" is relatively genteel. $135,000 buys a trip to Iceland, Norway and Latvia, where the work is legal, and the women are over 18 and well paid. And if they don't exactly love what they do, they enjoy it as much as anyone who, say, sells floor tile or works in a bank.

Jankowsky still carries the wounds incurred growing up with a mother who married four times. He has trouble sustaining relationships. So does his live-in girlfriend, Deirdre, who confesses one day to sleeping with a fellow grad student at Columbia University.

Then a once-in-a-lifetime chance to earn $400,000 by writing a book about a sex tour comes knocking. That's enough to buy a new apartment, even in the Apple, and escape from Deirdre.

Once on the tour, Jankowsky doesn't stop at writing. Despite his determination not to participate, he is, like all of us, Spencer argues, a slave to a universal itch. He succumbs in a few deftly written, ungratuitous sex scenes.

Jankowsky is both an amusing and musing character -- perhaps too inward-gazing, not unlike Richard Ford's sportswriter at times. But his mingling with his new companions makes this novel worth the trip.

Ten or so men board the Fleming Tours refurbished 737 -- a former pro basketball star, the obese founder of Piedmont Computers, a regular schmo who won the lottery. There's a kid who lost an arm and half his face in Iraq.

Each man merits at least a modicum of interest and sympathy. Even the most loathsome customer, one who drags a hooker around the halls of a fancy hotel, tells a story about his late wife's cervical cancer that reveals a capacity for love.

We also get acquainted with the prostitutes -- treated by the author with a similar unsentimental compassion. In Reykjavik, a hooker named Sigrid talks with Jankowsky in awkward English about her ordinaryness, in dialog that never seems ordinary.

In Oslo, Jankowsky meets Nina, who plays in a punkish band and needs money to replace her boyfriend's guitar, stolen from their tour van.

As the rakes progress from city to city, what seemed like a can't-miss good time wiggles away. The men quarrel. Thugs attack them. Then Jankowsky's mother shows up, for a generally satisfying conclusion that forces the narrator to confront his own deficiencies.

The early pages have a little trouble gaining traction. The initial scenes in New York occasionally recall something you've read before about young neurotic intellectuals in love.

At one point, the plot's pulleys crank furiously to introduce Jankowsky's rich Uncle Ezra, to whom Castle just happens to owe a free sex tour.

But after that, nothing is pat or predictable or rendered with cheap emotion. Spencer -- a graceful and original stylist who may remind the reader of Ford or Nick Hornby or even the humorous reprieves in Philip Roth -- tells a story that is, well, seductive.