By Nina Killham

Bloomsbury. 259 pp. $22.95

The premise of Nina Killham's thoroughly amusing (and deliciously titled) second novel is fairly ridiculous but beguiling all the same. Jack Carter writes romantic novels under the pseudonym of Celeste D'Arcy and makes a "very comfortable living" from it. His books, which include "The Rusty Rake" and "Withering Heights," feature "raging literary alpha males" -- Shane Masters, Gaston Drake, Beau Honore -- "who tantalized deserving females until they begged for mercy." But Jack himself is something else altogether. His wife has walked out on him and, though plenty of ladies seek his favors, he has decided to become "a born-again virgin." That's that:

"So no more Wham, bam, thank you, sir. He was going to remain celibate until he discovered a woman who would keep her hands to herself until she committed to him. And only when they had grown to love and trust each other would they lie down and allow their passion to combust into a raging physical blaze."

In Venice Beach? Get real. That hip enclave in Los Angeles positively reeks of sex, what with everyone slinking around in bikinis and thongs and strings, and the ocean roaring its sensuous roar, and Hollywood right around the corner where everyone is willing to trade a favor for a part. No, the odds are hopelessly against Jack, and they become even more so when his sister, Kate, who's so frigid her marriage threatens to "explode into ice-cold fragments," asks him to do her a favor: take in as a boarder her friend Molly, "a woman who liked to work hard and play hard," who counts a day lost unless she's had sex with at least one man. As she tells her Sex and Love Addicts meeting, " 'I'm a sexaholic. . . . I've been sexually sober for' -- Molly glanced at her watch -- 'approximately seventy-five minutes.' "

Jack reluctantly takes her in, assigning her to a bedroom as far from his own as possible. She alternately baits him and teases him, but he stands firm. He's had it right up to here, and he's not going to take it anymore. As he puts it:

"Wouldn't it be nice if everybody went about their business without sex screaming at them from every angle? Toothpaste will give you shinier, sexier teeth. Eat Super Cereal Plus for that sleek, sexy body. . . . You know, I just saw an ad that showed this woman having an orgasm while she was using Drano. . . . I'm saying who needs to have sex anymore? Who needs to see a female body anymore? Or a male one. We've got naked bodies draped all over the place. Everyone is grunting and groaning all around me. I just want everyone to shut up about it."

So Jack stubbornly goes about his business, plugging away at his computer, writing the story of Primrose Dubois, "his plucky firecracker of a governess," and Guy Courage, "blazing blue eyes, tall, slim hips tapering into long muscular legs, a chest like molded armor, a jaw to crack a nut with." Meantime, in the other room, Molly goes about her business, with the FedEx man or the plumber or anything else in pants that shows up at the front door. The grunting and groaning that issue forth from her quarters can be a trifle distracting, but Jack is determined. He presses on.

Then a funny thing happens: Molly gets the writing bug and starts a novel. It's all sex and no romance, all big passion and bad prose. Jack can see it's no good, but if writing it makes her happy and keeps her out of his hair -- not to mention his pants -- well, write on. Soon enough, though, a not-so-funny thing happens. While Molly merrily types away, Jack -- for the first time in his life -- comes down with writer's block. He wonders if he shouldn't get a real job:

"If this writer's block lasted, he calculated that he had about six months before it was time to downgrade to a two-bedroom in Studio City. The problem was that after a certain age, writers were basically unemployable. They were entirely too individual to be team players. Too opinionated, too charmed by the sound of their own mental mastication. They knew a little about everything and not enough about anything. Of course, he had done so much research on his last book, he could probably walk into an auction house and get a job as a Regency appraiser. And a few years ago he had managed a passable medical romance: no doubt he could fudge a day or two as a nurse. It was too bad there weren't a lot of openings for high-seas pirates, because he really knew the ins and outs of that field. Jack sighed. If his sales didn't pick up, he was in serious trouble."

He's in serious trouble anyway, thanks to Molly and his vow of chastity, as well as his mother, who's been kicked out of her nursing home for excessive randiness. She shows up demanding shelter, and how can a boy turn down Mom, even if by her own reckoning she looks like "Richard Milhous Nixon in drag" and is making moves on an old guy in a wheelchair who claims to be a former ambassador but is actually a former car salesman. Suddenly Jack's house in Venice Beach is throbbing with libidos, repressed and otherwise.

To make things just a little bit worse, Jack's shrink won't see him anymore; he thinks the born-again-virgin bit is wacko. When Jack insists, he relents to the extent of referring him to a small group of guys "sitting on the benches outside Victoria's Secret, watching the parade of teenage girls wandering in and out." Soon they welcome Jack into their circle and teach him their ritual chant:

"Who are we?"

"Born-again virgins!"

"What will we stay?"

"Born-again virgins!"

"What are we waiting for?"

"Love! True love! Rah! Rah! Rah!"

On and on "Mounting Desire" goes, part ridiculous, part sublime. Nina Killham, previously unknown to me, turns out to be a comic writer of genuine gifts. She was born in Washington and wrote about food for The Washington Post, though her path and mine never crossed. She's lived for some years in London but she obviously keeps a close eye on doings on this side of the Atlantic. Her sendup of romance novels is spot on, not merely those who write and read them but those who publish them; Jack's editor, Lucinda Burrows, is an absolutely delicious spoof who swoops down from New York, takes Jack "to high tea at the Bel Air Hotel" and tells him how "divine" he is.

There is of course, amid all the laughter, a serious point here. Sex indeed is too much with us, in too public and too cynically commercial ways, and a bit of toning down indeed is in order. Swearing off it completely may not be the answer, but in an age where it all hangs out, a little reticence would be nice. Killham makes the point deftly in this very funny, very clever, very adult novel.