Neal Stephenson's new novel is a departure from the epic science-fiction sagas with which he transformed the genre in the 1990s and 2000s. Like some of his previous books, Reamde (William Morrow, 1,056 pages, $35) is too long, it's cluttered with computers, and it comes wrapped in a mostly black dust jacket, but it's not science fiction or historical fantasy. It's a realistic, present-day adventure thriller that explores what could happen if a war in the online gaming world spilled over into the real world of hackers, mobsters, terrorists and spies.

The main character, Richard Forthrast, is a secretive multimillionaire who amassed his initial fortune smuggling marijuana across the Canadian border while dodging the draft during the Vietnam War. He later creates T'Rain, a World of Warcraft-style online role-playing game for the purpose of laundering the proceeds: Instead of preventing Chinese kids from farming the game for virtual gold they can sell to affluent Western players, T'Rain encourages the trade. Forthrast collects from online buyers who pay by credit card and then pays off the gold farmers with aging $100 bills squirreled away from his drug-smuggling days.

Trouble starts when a young Chinese hacker tries to cash in on this virtual economy by creating a readme file (misspelled "reamde") that encrypts T'Rain players' personal computer files. To get the code needed to decrypt them, players must deposit a ransom in virtual gold, fueling an online war as bandits ambush victims for their ransom money.

Forthrast's adopted niece, Zula, is kidnapped by the Russian mafia when her self-absorbed boyfriend, Peter, unwittingly sells the mob a file of stolen credit card numbers infected with the reamde virus. Zula and Peter are shanghaied to China to help track down the author of reamde, but the action powers up to the next level when the Russians clash by mistake with a cell of Islamic terrorists, and Zula falls into the hands of a bin Laden-style jihadist. From there, the stakes are raised from the merely personal to the potentially global.

Reamde is easily 400 pages too long. Stephenson can't resist describing his characters' every thought and movement in minute detail, whether they're designing believable topography for an online fantasy world or trying to shoot a terrorist in the head with a Makarov 9mm after forgetting to cock it. But for readers with the patience to unzip Reamde's dense, high-resolution narrative, the choice is clear: reaidt.

SEE IT: Neal Stephenson reads at the Bagdad Theater, 3702 SE Hawthorne Blvd., 236-9234. 7 pm Thursday, Sept. 22. $10.