A new book from Thomas Pynchon is always a big deal. Fans may not camp out in front of bookstores Harry Potter-style, but bookish people celebrate new novels from the reclusive author in an excited, covetous mood that most people reserve for expensive tickets to rock concerts. The release of Inherent Vice (it went on sale Tuesday, August 4) is an especially big deal. It doesn't resemble the physical shape of his other novels, which are traditionally ponderous and sprawling and messy. And while many of his books toy with genre, the slim, breezy Vice is unabashedly a mystery.

Everything about Vice, from its ugly, neon-lettered cover to its down-on-his-luck private investigator Doc Sportello, positively reeks with the pungent odor of the dime-store gumshoe thriller. It begins, as all good mysteries do, with a woman from Doc's past ("Tonight she was all in flatland gear, hair a lot shorter than he remembered, looking just like she swore she'd never look") wandering back into his life with a problem in tow. Vice is set in the late '60s and Doc is an unrepentant, dope-smoking dropout, the backwash of the Woodstock generation. He smokes his joints down to nothingness and his memory is a clouded, cottony haze.

Doc "automotively gropes" around Los Angeles in his nondescript car, not so much actively trying to solve the mystery as asking his friends what they think he should do about it. Along the way, an enormous conspiracy controlled by an organization called the Golden Fang distracts him. It's a name right out of a Sax Rohmer Fu Manchu thriller, and the building that may or may not serve as the organization's headquarters is pure pulp: a six-story ornate golden fang, supposedly populated with dentists' offices.

Pynchon hasn't been this accessible since The Crying of Lot 49. He's obviously having fun, and it's hard not to picture him giggling at his typewriter as he plowed through page after page of Vice. The narrative is festooned with digressions and details that mirror Doc's addle-brained thought processes and also function as a kind of secondary language, making Vice a tone poem constructed from American cultural detritus.

Like any paranoid ex-hippie, Doc maintains a healthy belief in conspiracies. As he searches for someone named Wolfmann, he keeps uncovering information about Atlantis and its lesser-known Pacific Ocean sister city, Lemuria. Doc wrestles with these layers of conspiracy, many of which don't exist until his pot-fogged brain creates them, and reveals the book's central conflict: Vice is about the way our practical, hairy ape brains can scuttle their own ambitions by idly creating strange fictions that then become too real to ignore. It's a battle that has raged through most of Pynchon's work in one way or another.

Beneath it all, surfacing sporadically like a cheap serial villain, is the nascent internet, which in the late '60s was called the ARPAnet. One of Doc's friends introduces him to the prototypical World Wide Web, and he increasingly relies on it for information. He wonders why "they"—the men he's positive rule the world from a smoke-filled room—don't make it illegal, the way "they" criminalized acid. Pynchon, doing some of the nimblest, most whimsical work of his career, doesn't provide the answer to that mystery, or many of the mysteries in Vice for that matter, but he shares his infectious excitement about living in a world full of useless, beautiful ideas. For Pynchon, it's not the truth but the search for the truth that matters.