By Michael Connelly

Little, Brown. 405 pp. $25.95

"The Narrows," Michael Connelly's 14th book, is a page-turning continuation of a story begun in his best-selling "The Poet." It pits ex-Los Angeles homicide detective and current private investigator Harry Bosch and his former protege, the disgraced Rachel Walling, against the FBI behavioral scientist-turned-serial killer Robert Backus in a classic game of cat and mouse. "The Narrows" refers to the system of aqueducts throughout the L.A. area, large concrete entrapments that sit benignly empty much of the time but churn with water, debris and death during torrential rains. They form the symbolic underpinnings of the novel.

Bosch is drawn into the case when the widow of an old friend asks him to investigate her husband's suspicious death. The apparent heart attack that killed Terry McCaleb -- the primary character of Connelly's novel "Blood Work," which was adapted into a film starring Clint Eastwood -- turns out to be something else. At the same time, Walling, the young FBI agent banished to South Dakota for her failures in "The Poet," is summoned to the Nevada desert, where forensic specialists are excavating a half-dozen bodies. Meanwhile, a hand-held GPS (global positioning system) locator sent to the FBI leads the agency to discover that Backus, long believed dead, is alive and pursuing his macabre trade.

In short order, Bosch uncovers what seems to be a very clever homicide and, while vetting computer notes found in his friend's boat, is inexorably led to Las Vegas and the crime scene in the Nevada desert. He crosses paths with Walling, and the two link up to outmaneuver Backus -- no mean feat, since he is the guy who pretty much wrote the manual on how to catch a serial killer. This gives Backus a significant advantage over the run-of-the-mill agents who are at least as concerned with making sure they don't screw up as they are with succeeding. It does not, however, provide him with a proverbial leg up on Harry Bosch, an outside-the-box thinker whose loose-cannon, bull-in-the-china-shop approach to murder investigations has endeared him to a legion of mystery fans.

While Bosch and Walling trail Backus, he stalks them. Eventually "The Narrows" becomes a race to see which side will outwit the other. Along the way, some folks get killed, some prostitutes at a legal Nevada brothel get some snappy lines, some FBI agents prove that bureaucracy lacks creativity, some sex is engaged in, some homes get rigged to explode (and do). Harry Bosch proves his value once again, and Rachel Walling demonstrates that disgrace can be a steppingstone to ingenuity. Connelly knows his forensic evidence and his serial killers, and he is very good on crime-solving techniques and processing -- both physical and mental.

"The Narrows" is very much a sequel, and in that respect it has a little trouble standing on its own. Connelly frequently refers to the events of the preceding book, and just as often relies on the reader's knowledge of "Blood Work" and the Eastwood film. It is perhaps unfair to judge a sequel by the same standards applied to a conventional novel. In all likelihood, readers familiar with these prior works would be frustrated by much explication, either of plot or of character, that they might consider repetitive. Consequently, there isn't much background -- "The Narrows" simply sails right off into its story. This makes it a tricky read for those coming to Connelly for the first time. They will discover that he has an attractive rapid-fire writing style and that he skillfully deliversthekey pieces of evidence that tie the strands of the story together. But his reliance on information from previous books means that appreciating this one is something of a challenge.

Perhaps the most curious thing about the novel is its somewhat passionless final confrontation between serial killer Backus and the constantly clever Bosch. As expected in these sorts of books, Connelly provides gunfire, conversation, a chase and a fight, all hung on the appropriate cliff. But all of it takes place in a matter-of-fact style that doesn't do full justice to a battle between good and evil of such dimension that it requires two novels to encompass it.

Nonetheless, fans of Harry Bosch undoubtedly will be pleased. Although "The Narrows" is unlikely to win many new admirers, it will satisfy those who have already bought into the stories of Bosch. In the final pages, Connelly explains that the retired detective has been offered a chance to re-up with the LAPD. This promises new intrigues, now that those posed by the Poet have been dispensed with.