By J.K. Rowling

Illustrations by Mary Grandpre

Arthur A. Levine/Scholastic. 341 pp. $17.95

Once there were Choose Your Own Adventures. Then came the horror novels of R.L. Stine. Which were followed by Brian Jacques's sword-and-rodent swashbucklers set around Redwall Abbey. But, hot as these once were among 9- to 12-year-olds, their popularity hardly compares with that of the almost supernatural success of J.K. Rowling's Harry Potter novels. Last year, Harry Potter and the Sorcerer's Stone -- written by an impoverished single mother, in coffee shops -- kept thousands of middle-school kids up all hours, even till dawn, reading hollow-eyed, unable to stop turning pages. The novel was the talk of classrooms and playgrounds; it was bought, borrowed and checked out of libraries; pre-teen word of mouth kept it on bestseller lists for months.

In his first adventure, the skinny, bespectacled Harry Potter discovers that he is -- the conviction of every 12-year-old -- no ordinary kid. Yes, he has been brought up in our world by his repulsive aunt and uncle, the Dursleys, who work him like a beast. Yes, their son, the grossly fat Dudley, gleefully torments him. And yes, he is regularly insulted, exploited and ignored. In fact, his misery quite rivals that of Cinderella before she meets her fairy godmother. Like that heroine, Harry soon discovers that things are not quite what they seem.

For Harry Potter may be the most powerful wizard in the world. Or rather in the magical world parallel to our own. His mother and father didn't die in a blazing automobile accident. In fact, they were powerful magicians who perished fighting valiantly against the dark Lord Voldemort. Yet their child survived the evil necromancer's attacks. And more than that. In some obscure way, Voldemort was himself thwarted by the infant Harry, who bears a lightning-shaped scar on his forehead as a souvenir of the encounter. Since that mysterious day He-Who-Must-Not-Be-Named has never been seen. But has he been destroyed? Or is he simply biding his time?

In due course, Harry Potter escapes the clutches of his "Muggle" -- that is, human -- relatives with the help of the seemingly slow-witted, gigantic Hagrid. Accepted at Hogwarts School for Witchcraft and Wizardry, he makes friends there with ginger-haired Ron Weasley, scion of a famous if impoverished pure-blood wizard family, and Hermione Granger, a Muggle with phenomenal magical gifts. He also encounters the snide and disdainful Draco Malfoy, son of the arrogant Lord Malfoy, who was once a close associate of You Know Who. Many thrilling adventures ensue during the school year, culminating in a horrifying combat with the Dark Lord himself.

This novel -- a heady brew of Roald Dahl, E. Nesbit, the Hardy Boys, and "Star Wars" -- proved utterly irresistible to 9- to 12-year-olds of any age (this reviewer included). Rowling's prose wasn't particularly remarkable or witty, but she clearly knew how to keep a story moving along, and her instincts for what kids like in a book were unerring. School rivalries, sports (the Hogwarts students play a version of airborne soccer called Quidditch), close friendships, admiration for certain elders (the wise wizard Dumbledore), dislike for the pompous (the oily potions master Snape), mysteries, rule-breaking, great battles against odds, and ultimate triumph for Harry and his comrades -- such a combination couldn't fail.

And what has worked once should work twice, right? So Rowling has essentially repeated the general pattern in this follow-up adventure, Harry Potter and the Chamber of Secrets. It opens with Harry, back with the Dursleys for the summer, receiving an unexpected visitor: a house elf named Dobby imploring him never to return to Hogwarts. The dangers that await him there are life-threatening, but Dobby can say no more. Nothing daunted, Harry finds himself rescued from summer bondage to his Muggle relatives by Ron Weasley, who has "borrowed" his father's ensorcelled flying automobile. Before long, Harry's old gang is once more reunited at Hogwarts, where, at first, everything seems the same.

There has been, however, an addition to the school's staff: The famous Gilderoy Lockhart -- author of "Gadding with Ghouls," "Travels with Trolls," "Voyages with Vampires," "Wandering with Werewolves," and "Year with the Yeti," among other books -- has been hired to teach the course on Defense Against the Dark Arts. Gilderoy, "winner of Witch Weekly's Most-Charming-Smile Award five times in a row," is a wonderfully smarmy charlatan, possessed of virtually no magical talent whatsoever beyond that of public relations. Alas, Hogwarts will soon need a real defender against the dark arts.

For Harry starts to hear hissing voices, whispering of blood and death. Is he imagining things? he wonders. No such luck. On the evening of the Halloween feast, Harry, Ron and Hermione stumble across a horrible sight -- a proctor's cat, turned to stone, hanging by her tail from a torch bracket. On the wall above the petrified animal "foot-high words had been daubed. . . THE CHAMBER OF SECRETS HAS BEEN OPENED. ENEMIES OF THE HEIR, BEWARE."

Soon the entire school is awash in suspicion. Who is the heir of Slytherin, one of four ancient magicians who helped found Hogwarts and possessed the power to talk to snakes? Could it be Harry? Or is it Draco? Or might it be someone utterly unexpected? Matters grow scarier when one of the students is petrified, and then another. Both were Muggles. It would seem that some monster delights in destroying any with less than pure wizard blood. Can Harry Potter and company find the Chamber of Secrets and defeat this creature from the past?

A mysterious diary, gigantic spiders, ancient magic, a ghost who lives in the girl's restroom, a flying car that arrives like the cavalry in a Western, a bejeweled sword, the legendary phoenix -- all these play their parts before the underground finale of Harry Potter and the Chamber of Secrets. Voldemort, it goes without saying, is behind everything, though not quite in the way you expect.

Children who loved Harry Potter and the Sorcerer's Stone -- and that means almost all those who read it -- will enjoy this new adventure, though the sequel seems slightly less magical than the original, if only because we've been here before. Still, kids at this age love series books just because they provide reliable, familiar pleasures. So, if you haven't bought it yet, do -- Harry Potter and the Chamber of Secrets is a perfect summer novel for any 9- to 12-year-old. And don't delay. Rumor has it that there will be another Harry Potter thriller this September. Some of us, despite our critical cavils, can hardly wait.

Michael Dirda's e-mail address is dirdam@washpost.com.