By Lee Child

Delacorte. 376 pp. $25

After an 18-year career in British television, Lee Child was downsized out of his job at age 40. A fan of American crime fiction, he decided to launch a series about a big, tough American ex-Army MP named Jack Reacher. On the theory that most crime-fiction heroes are too bland and likable, he decided to make Reacher "rough, snarling, dirty, unacceptable in every way." He largely succeeded. Reacher is essentially a killing machine with attitude. He's 6 feet 5, weighs 250 and is expert with his fists and every imaginable weapon. Child's premise is that Reacher spends his time moving around the United States with just the clothes on his back. He has no home, no car, no credit card -- he's a rambling man. He doesn't look for trouble, but it looks for him.

The Reacher books were successful from the first, at least in part because the protagonist is a great male fantasy. He's lethal, unencumbered and -- surprise! -- besides trouble, he keeps finding babes. But there's another reason for his popularity. Child writes well, and he's good at explaining things -- particularly weapons and the killing arts. Of the Reacher novels I've read, the best was "Without Fail," which had him protecting a U.S. vice president. Child had done his homework, and he gave an impressive picture of how the Secret Service defends the VP and how a determined assassin might penetrate its shield.

"One Shot," ninth in the series, is less satisfying. Often I didn't believe what was happening. It becomes a question of how much leeway you give a writer -- how much, as they say, you're willing to suspend disbelief. The best crime novels unfold effortlessly -- we never doubt them -- but they're rare. With most thrillers, you trade logic for a good time. For me, a lot depends on the writing. The ability to write well is like having a pretty face -- you can get away with a lot. Thomas Harris's Hannibal Lecter novels, if written by James Patterson, would be unbearable, but (assuming that you can handle the violence) Harris's intelligence, style and sublime perversity make his suave cannibal irresistible. Child is not as good as Harris, but he's light-years better than Patterson, and it becomes a question of overlooking -- or not overlooking -- soft spots in his plot.

The story is this: Reacher is making whoopee in South Beach with a six-foot Norwegian dancer when he sees on television that a sniper he knew during Operation Desert Storm has been arrested for shooting five people, apparently at random, in an Indiana town. Reacher, short on funds, rides the bus there and starts poking around. The police think they have a slam-dunk case against the sniper, but Reacher suspects a frame-up. Soon some Russian gangsters have framed Reacher for another murder and the police are after him. The first thing we have to accept is that this giant of a man, who has no car and mostly walks the streets, could avoid both the cops and the murderous Russians until late in the novel.

Then there are the gangsters themselves. Their 80-year-old leader, "an old bull" of a man, fought at Stalingrad and then spent more than 30 years in the gulag. He has "only a thumb and a single finger remaining on each hand," and he leads a bunch of killers who were Red Army soldiers before they sought new opportunities in America. We have to accept that these merry pranksters could run a business in the heartland, kill people, corrupt local officials and yet escape notice until Reacher came along. We have to accept that when one of these bloodthirsty Russians twice gets the drop on an unarmed Reacher, he spares him for reasons that are more convenient than logical. And that it isn't until Page 212 that someone -- Reacher, of course -- finally asks the rather obvious question of why the sniper shot the five people in the first place.

Child is a skillful writer, but at its worst this book reads like one of those really lame thrillers where bad guys who limp or have a scar on their face slink around wielding diabolical powers until the hero outfoxes them. Part of the problem is that today's successful thriller writers are under pressure to produce a book a year, and they may not have a first-rate story to tell every year. Less is more, but try to tell that to a publisher. Still, if you're a Reacher fan, if you think he's cool or sexy, then you'll suspend disbelief, buy into the plot and have a good time with "One Shot," which is always readable and features neat dialogue. "So you're cool?" a man asks. "You could skate on me," our guy declares. "You're new in town, aren't you?" a woman says. "Usually," he replies. A Marine marksman says, "I don't care much for handguns. No art to them."

Reacher offers an unsentimental theory of the four types who join the Army: those for whom it's a family tradition, patriots, people who need a job and "people who want to kill other people." Reacher, who attended West Point, puts himself in the first category, but he's not so far from the last one.

In a nicely choreographed scene, our one-man army, carrying only a knife, invades a house packed with Russian assassins, does his duty, then hits the highway. He's leaving several unhappy women behind, but he's happy because "he could . . . be just about anywhere before the sun went down again." Sounds cool to me.