By Scott Bradfield. Carroll & Graf. 251 pp. Paperback, $13

If Beverly Cleary's Ramona the Pest had grown up in a dysfunctional home, run away at age 12 and moved in with Iris -- the pre-teen flesh trade worker in "Taxi Driver" -- she might have grown up to be like Delilah Riordan, the plucky heroine of Scott Bradfield's dark comedy Good Girl Wants It Bad. Delilah -- "Lah" for short, just as Lolita was "Lo" -- is a bubblegum bimbo with black-widow allure, a death-row hottie with long, long legs and a matching rap sheet (serial murder, torture and sex crimes). As Lah languishes in the West Texas Women's Facility, awaiting her final injection, wardens, therapists, correction officers and other inmates buzz around her like gnats on a melon, hoping for a last chance at the forbidden fruit, even if they know that everyone who has sampled the feast has ended up dead and sometimes disemboweled (once with pinking shears). To their intense gratification, Lah nearly always complies with her admirers' desires, which raises the question: How dangerously bonkers does a good-looking woman have to be before men cease fantasizing about her? If Bradfield's yarn is any answer, there is no upper limit. (If nothing else, his book is a vivid illustration of the cartoonist Matt Groening's precept, from his pre-Simpsons days, that "men are stupid and women are crazy.")

Not that Lah would agree that she's crazy. In her own opinion, she is "a good girl with normal human emotions who enjoys the company of men." As she explains to Dr. Pendenning, one of the lust-blinded prison doctors who tend her, "I happen to like men very much. A lot more than women, if you must know." Nor does she see herself as a serial killer and torturer. "Serial killing is an entirely inappropriate label for a young woman like myself, who has never been anything like a serial killer," she protests, with sugar-coated opacity. "The facts speak for themselves. . . . First off, I have not killed that many people, maybe two, though there have been several accidents involving men I knew, one of whom I actually loved." Also, she adds, "I do not eat people, since I'm practically a vegan." There you go -- she's as normal as blueberry pie. Want to try a piece? It may be your last.

Most of the book's macabre fun comes from the preposterous notion that this sexpot dingbat would be capable of committing the grisly murders she's accused of -- gut-shooting a father of three; poisoning an old sugar daddy; strangling and mangling a used-car dealer and dumping his parts in a landfill, trash bins, a sewage plant (etc.); bludgeoning an exotic dancer with a sex toy during the making of an erotic film; slicing and dicing a handsome cowboy who was "a great dancer and has very big hands and you know what that means"; and so on. While Lah freely concedes that this string of atrocities popped up along her itinerary as she toured the country in a camper, she puts it down to coincidence, and accuses the reporters and legal professionals who pin each new crime on her of laziness. "If there's no motive, you did it. If nobody knows who did it, you did it. If nobody knows a reason why anybody might do it, you did it. It's so illogical and unfair, but is definitely the way law enforcement works today."

And yet . . . did Delilah Riordan commit the crimes she's accused of? Since Bradfield presents her tale as a series of self-serving, self-contradictory confessions, Lah is by intention an unreliable narrator. Sometimes she seems to admit her guilt, as when she incautiously muses, while watching one of her suitors break down: "Now Dr. Reginald is crying, all balled up in his chair, convulsing, like somebody you've tied up and partly eviscerated and they know they're going to die and you won't be merciful, it's no secret anymore. . . . Being merciful is for suckers." Other times, she implies that her ex-boyfriend Manuel, whose only words of English are "I love you," has committed the murders: "Say you have a very jealous boyfriend capable of terrible rages who follows you around the country, even when you least expect it," she hints. And there's even an insinuation that her father might have been involved in a bloody demise or two.

So which is it? Did Lah commit the crimes? Did Manuel? Did her father? If Lah was the culprit, did she polish off her victims with inexplicable glee -- which is the element of frisk that keeps the novel from being merely a titillating rumination on the sexual insatiability of a sadistic murderess? Or did she do it because, in daytime scandal-show boilerplate, she's a victim herself, a pitiable survivor of abuse and neglect? If Lah were to turn out not to be a serial killer after all, should she be let back on the streets -- is she really a good girl? The answer seems to be: You'd better not ask a man. "Men are always looking for reasons to distrust women," Delilah says early on in her own defense. But as Bradfield shows, the mistake the men who meet Lah make is trusting her too much when they should be running for cover. *

Liesl Schillinger is an arts editor at the New Yorker.