If the Harry Potter books taught kids about the British class system and the arcane rules of a game called quidditch, then Percy Jackson and the Olympians: The Lightning Thief is already a cut above for schooling its young audience on Greek mythology and its fiery, contentious gods and goddesses. That’s the part of novelist Rick Riordan’s best-selling chapter book The Lightning Thief that thrills parents who want their children to learn more Hades, Athena, Zeus, and Mt. Olympus.

For kids, there’s the wonderfully ordinary teenage hero Percy Jackson, who suffers from dyslexia and ADHD (a nod to Riordan’s own son). Interestingly, his disabilities are not really disabilities at all; they’re proof that he is the demigod son of Poseidon and a mortal mother. The Lightning Thief takes the standard fairy tale plot about a regular kid who discovers he’s really a prince and adds a contemporary twist to it: the fathers of all of these demigod children are supernatural, skyscraper-tall deadbeat dads.

Percy Jackson (Logan Lerman) lives in a grotty New York City walk-up with his mother Sally (Catherine Keener, now the official beaten-down, slacker mother of children’s book adaptations). Percy suffers both an oafish Homer Simpsonesque stepfather and the kind of rough inner-city school where students break out in fist fights with startling frequency. Like nearly every other recent work of literature geared toward children, The Lightning Thief is a tale of magic powers, secret identities, noble birth, and a protagonist who discovers he has a calling greater than homework.

When Percy’s demigod status is revealed, his mother is kidnapped and taken to the underworld by Hades, who has the mistaken idea that her son has stolen lightening from the gods. Percy then decides to rescue his mum, but first he must hone his fighting skills at Camp Half Blood, which is presided over by the centaur Chiron (Pierce Brosnan) sporting a glossy Fabio mane and a body like Flicka. At Half Blood, Percy hooks up with the blue-eyed, athletic (and gorgeous to boot) demigod daughter of Athena, Annabeth (Alexandra Daddario) and the wise-cracking goat-legged satyr Grover (Brandon T. Jackson). In this Odyssey for the iPod age (in a particularly devious bit of product placement, the device’s reflective surface is used to outwit Medusa), the trio gambol across America, from Knoxville to Vegas, in search of the magic pearls that will allow them to escape Hades once Percy’s mother is retrieved. In this adventure that occasionally feels like a video game, the trio battle nine-headed Hydras, Uma Thurman as a very Tallulah Bankhead Medusa, and other monsters that look like beasties out of a combo of Pan’s Labyrinth and Ray Harryhausen. The trio gets waylaid in Las Vegas when they eat the narcotic lotus flowers, which temporarily distracts them with pretty girls, dancing, and fun, before Percy shakes off the spell and remembers his quest. Perhaps the film’s best sequence, the Vegas interlude is a mildly creepy implicit cautionary tale about getting lost in some neon-lit sex-and-vice netherworld.

Yes, The Lightning Thief boasts a moderately derivative J.K. Rowling-set up of three Ron-Harry-Hermione-style friends using magic against their foes. The film, directed by Chris Columbus (Harry Potter and the Chamber of Secrets, Harry Potter and the Sorcerer’s Stone), also departs sharply from the book in many ways. One significant deviation involves transforming Percy’s satyr buddy Grover into the hackneyed, borderline-offensive stereotype of the wise-cracking, jive-talking black sidekick.

In other ways, The Lightning Thief is an admirable kid’s fantasy. For one, the film puts Athena’s daughter Annabeth on equal footing with the tale’s young male demigods.

If kids aren’t too disappointed by the alterations to their beloved book — and many of the giddy, wild-eyed Lightening acolytes at a recent screening didn’t seem to mind — 2010 may have its first tween-and-under hit.