By Michael Crichton

Knopf. 450 pp. $26.95

Like a pack of velociraptors, the novels of Michael Crichton are evolutionarily honed to perform well in their niche. Efficient, unstoppable literary predators, they generally consume the lesser beasts in their domain (the bestseller lists) and outperform all their more sophisticated cousins (genre science-fiction books). But it also follows that Crichton's creatures are not necessarily graceful or pretty or altogether smart in their blunt slash-and-gobble methodology. His latest, "Timeline," is no exception.

A time-travel tale (with a small ontological twist), Crichton's new book suffers from two defects: slow buildup and a pedestrian adventure. The first 160 pages, which laboriously lay the groundwork for the actual chronological voyaging, include the introduction of several seemingly crucial characters who are later completely forgotten. This tedious ramping up will seem glacial to an sf-savvy audience that is used to seeing Michael J. Fox accomplish the same thing swiftly by popping into his De Lorean. And once the jump across the centuries has been accomplished, Crichton limits himself to a single mundane setting devoid of the kind of paradoxical conundrums or vast cosmological vistas implicit in the best time-travel stories.

The book opens with the mysterious death of a renegade scientist working for a firm known as ITC. The suspicions of the attending physician and her policeman friend, who are never in the foreground again after this episode, come to naught, as does the bluster of a French journalist introduced later and just as cavalierly dropped.

ITC is run by Robert Doniger, an amoral Ueber-Bill Gates figure, "thirty-eight years old, a brilliant physicist, and a billionaire." Doniger and company have perfected a kind of time travel that involves visiting parallel universes--slower out of the starting gate in relation to our own--where different historical eras still flourish. Now, this is hardly a new conceptual stroke. The modern fictional invention of parallel universes is generally credited to Murray Leinster in his story "Sidewise in Time." The concept reached some kind of pinnacle in Keith Laumer's slam-bang action series that began with "Worlds of the Imperium." But Crichton, and his villain Doniger, can think of nothing better to do with this monumental discovery than use it to create some very authentic "Westworld"-style theme parks for mind control and profit.

To those ends, Doniger has funded various teams of archaeologists to prep real-world sites where he intends to build. At one such, in the Dordogne region of France, we finally meet the real protagonists: Edward Johnston, "Regius Professor of History at Yale"; Andre Marek, an assistant professor in the mode of Indiana Jones; and two grad students, Chris Hughes, ladies' man, and Katherine Erickson, rock climber. When a balky Johnston is sent by a coercive Doniger on a trip back to medieval Dordogne, the professor becomes trapped in the past, prisoner of feuding warlords. The other three are sent to rescue him, in a kind of medieval "Mission: Impossible." And, for reasons I never quite found clear, given all of time as a playground, they have a mere 37 hours to complete their objective, providing Crichton with countdown-style pacing in the manner of "The Andromeda Strain."

Once back in the past, "Timeline," despite a few alternating chapters of present-day skulduggery, degenerates into a straight historical fiction with minor frissons involving the modern characters' bemused take on the foreign territory of the past. The political maneuverings among the natives and the details of quotidian life assume central importance, much as in, say, a Mary Renault novel. Crichton injects a bit of cross-era romance as perfected by Jack Finney in his "Time and Again" and a smidgen of wily savant hoaxing like that in Mark Twain's "Connecticut Yankee in King Arthur's Court." But for the majority of the story we're in Sir Walter Scott territory, having lost any real speculative edge.

Crichton deserves credit for buttressing fore and aft both the probability of his time-travel device and the accuracy of his period reconstructions with solid scientific and historical research. He manages to avoid the dreaded "info-dumps" of bad science fiction, inserting information cleverly into dialogue and small omniscient passages (although I still refuse to believe that time travelers in life-threatening danger would pause in mid-flight to discuss medieval tanning procedures). Readers eager to learn entertaining, little-known lore of the High Middle Ages will get their fill here.

Crichton's prose, though lumbering, is never less than transparent in its depiction of event and setting. Not surprisingly, given the book's inevitable transformation into film, a scene such as Kate Erickson's foray among the vaulted spaces of a castle's upper reaches is cinematically vivid. Of Crichton's characters, it is sufficient to say that they carry their plot burdens with adequate pasteboard panache. Perhaps the most vivid, aside from baddie Doniger, who finally meets an unconvincing justice delivered out of the blue, is Andre Marek. Like Edgar Rice Burroughs's John Carter of Mars, Marek is one of those heroes born out of his proper sphere, who finds true fulfillment only when transposed from our cerebral world to one of primitive action.

This subtext, in fact, is part of Crichton's characteristic distrust of science. Just as with the spectacular disasters of "Jurassic Park," the troubles in "Timeline" stem not only from avarice and hubris but also from a perceived inherent flaw in the very practice of science. Crichton's one paradigm is "Frankenstein," and his books revel more in the failure of science than its triumphs. An awkward hybrid, "Timeline" seems to fall between two camps of readers, fully satisfying neither the aficionado of science fiction nor the consumer of historical pageantry.