By Christopher Paolini

Knopf. 681 pp. $21

In the rarefied world of young-adult fantasy, Christopher Paolini is a true rarity: a young adult who writes the stuff rather than simply reading it. Not only that, he has already sprinted beyond the huffing pack of hack fantasy writers. "Eragon," the novel Paolini started when he was 15, was picked up by Knopf four years later, in 2003, and became a long-running bestseller. A couple of million copies are in print, and a movie is in the works, with Jeremy Irons and John Malkovich onboard. But "Eragon," starring a boy and a scene-stealing blue she-dragon, was just the first installment in a projected trilogy. Now comes Book 2, "Eldest," with an initial print run of 1.3 million and two questions begging to be answered: Is it any good, as opposed to merely precocious and popular? And what's it doing with a red dragon on the cover?

You have to read as far as Page 639 to find out about the red dragon, though here's a hint: The blue dragon is not happy about him. The question of merit is not so easily answered. Those who can't abide dragons, dwarves, elves, sword-clanging battles, invented languages, maps, and all of the other staples of a certain well-worked strain of fantasy shouldn't even crack open the so-called Inheritance trilogy. And fans of the genre's luminaries -- Tolkien being the great progenitor -- may well split over "Eldest" as they did over "Eragon," some dismissing it as formulaic apprentice work, some detecting a strong voice already putting an individual spin on the conventions.

Both have a point. Told baldly, the plot thus far creaks with cliches. In "Eragon," an apparently orphaned farm boy living in the vaguely medieval empire of Alagaesia finds a blue stone egg, out of which hatches the lovable, glittering dragon and alter ego he names Saphira. But the pairing isn't accidental; nothing in fantasyland ever is. In a predictable melding of coming-of-age yarn, quest epic and good-vs.-evil clash, Eragon learns he is a Dragon Rider, the only one left besides the despotic King Galbatorix. Before Eragon and Saphira know it, the king's ghastly henchmen are after them, and the tutelage that will turn Eragon from a "slight, moody, overeager boy" into the empire's savior has begun. This involves a lot of explication by various tutors, a good deal of fortunetelling and much trekking about as rebels of all races start to gravitate to Eragon. The whole thing culminates in the first big, and necessarily inconclusive, clash with Galbatorix's army. Oh, and there's a hot elf maiden, she who lost Saphira's egg in the first place.

"Eldest" picks up right after the battle, with Eragon being handed off from his human and dwarf mentors to the elves for further lessons in magic, ancient words, warfare, politics and heartbreak (thank you, elf maiden). There is more sojourning, more brooding on destiny and identity, much New Age philosophizing from the elves (a race of vegetarian, workout-addicted conservationists: sort of Hollywoodites with pointy ears) and a lot of high-flown prose: "He shuddered and felt a hard core of determination coalesce in his belly. We have remained sequestered from the world for far too long. It's high time we leave Ellesmera and confront our fate, whatever it may be."

Meanwhile, interspersed chapters revert to the home front, Alagaesia, where Eragon's cousin Roran is mounting a small but exciting rescue mission of his own, and to the rebels' base in the south, where revolt is boiling up again. All these threads knit together -- neatly, it must be said -- at a second, even greater, climactic battle. It gives away nothing to say that this clash involves a betrayal, which was predicted umpteen pages earlier, and ends in a way that necessitates a third book. The traitor, by the way, is the rider of that puzzling red dragon and the source of the obscure title (though I still don't get why it's "eldest" and not "elder" -- unless that, too, signals a coming plot twist).

So. The plot and characters are largely derivative, not just of Tolkien but of Anne McCaffrey, Ursula K. Le Guin and others, as many readers have noted, and the prose is often hackneyed and in need of pruning. (It's telling that Eragon is 15 at the start of Book 1 and still just 16 at the end of Book 2, nearly 1,200 pages later.)

And yet, there's a saving spark. About three-quarters of the way through "Eldest," Eragon shows his elf mentor a poem he has written. "Rough but true," is the verdict, which is actually generous as regards the poem but acute as regards the novel. Despite his story's roughness, there are signs that Paolini is the real deal, something more than just a product of clever promotion.

One sign is the presence of characters who are allowed to voice a preemptive skepticism. My favorite is Angela the herbalist, who Paolini has said is based on his sister. "Everyone . . . is so serious and noble," Angela sighs, rightly. "They're probably all doomed to tragic deaths anyway." Orik the dwarf and Clovis the seaman are reliably tart-tongued. Even Saphira, who usually talks like a particularly platitudinous school counselor, occasionally turns playful: "Since she first breathed fire . . . Saphira had been insufferably proud of her new talent. She was constantly releasing little jets of flame, and she took every opportunity to light objects ablaze." In a genre that takes itself with suffocating seriousness, such humor is more than light relief: It's the sign of a writer struggling to make a set of conventions his own.

Here and there, too, one finds the cliches redeemed by sharp observation and unexpected riffs. Dragons are stale, but not a pair that crouch "like gem-studded bluffs." A deadly whirlpool at sea is nothing new, but we sit up when we read how a ship's keel "chattered across the puckered water" to pull away from it. Whenever the focus is on dragons or ships, in fact, or faerie architecture or weapons or a dozen other arcane topics, something engages and the writing simply soars.

"Eldest" isn't extraordinary, though it has its extraordinary moments. But me, I'm waiting for Paolini's sister to write a book.