Almost two decades have elapsed since Vernor Vinge won the Hugo Award for his epic 1992 space opera, A Fire Upon the Deep. Now he returns to Tines World with a sequel, The Children of the Sky (Tor, 444 pages, $25.99), to pick up the story of Ravna, the orphans Jefri and Johanna, and the 150 or so children left in coldsleep after their colony ship crash-landed on the planet in the earlier book.

The "Children of the Sky," sad to say, are growing up into the Adults Stuck on the Ground.

Much of the appeal of the first novel lay in its sheer scope. A Fire Upon the Deep ranged across half the Milky Way galaxy. The Children of the Sky spans barely half a planet. And despite some captivating fauna, including the doglike Tines who exhibit human-level intelligence and can communicate telepathically when formed into packs, Tines World is not sufficiently different from Earth.

The planet has arctic and tropical regions as well as the four usual seasons, meaning it revolves like Earth on a tilted axis as it orbits its sun. The Tines' Domain, ruled by a queen pack named Woodcarver, is located in the western portion of a North America-like continent with an East Coast run by a crazy wheeler-dealer pack of Tines named Tycoon, a sort of canine Sam Walton with obsessive-compulsive disorder.

When last we left our heroes, Ravna's lover, Pham Nuwen, a reconstructed warrior of the Qeng Ho caste, had died invoking something called the Countermeasure to save Tines World from the Blight, an interstellar computer intelligence ravaging civilizations across the galaxy. Since the Milky Way is divided into zones where faster-than-light space travel and communication are impossible closer to the galactic core, the Countermeasure vastly expanded the galaxy's "Slow Zone" to include Tines World and trap the oncoming Blighter fleet some 30 light years away.

Now Ravna, the only adult human left on Tines World, has maybe a few centuries to raise the planet out of medievalism before the Blighter fleet recovers and attacks at near-light speeds. Meanwhile, the traitor pack Vendacious escapes and joins forces with Tycoon; someone steals the "radio cloaks" that dangerously empower packs to communicate telepathically over long distances; and a "Denier" cult, which casts doubt on the threat the Blight poses to humanity, is gaining strength among the Children.

The political intrigue, personal betrayal and twisting plot show promise, but Vinge handles them with about as much sophistication as a Heinlein young adult novel. Compared to most of his other work, this is Tine food.

READ: Vernor Vinge visits Powell's Books at Cedar Hills Crossing, 3415 SW Cedar Hills Blvd., Beaverton, 226-4681. 7 pm Saturday, Oct. 15. Free.