“In this lively yarn, Thomas Pynchon, working in an unaccustomed genre, provides a classic illustration of the principle that if you can remember the sixties, you weren’t there … or … if you were there, then you … or, wait, is it …” Once again, for his seventh novel, Inherent Vice, it sounds as if the author has furnished his own jacket copy, exploiting the doper humor that’s often been part of his signature.

This isn’t the only evidence of retreads. For the third time, Pynchon has set a story in the California counterculture, on each occasion finding some relaxation there from the more ambitious historical frameworks of his other books; out West, the pages are fewer and the sentences, too, are often shorter. After V. (1963) came The Crying of Lot 49 (1966) — a snappy contemporary quest for signs of WASTE, a centuries-old alternative to the American postal system that might be the heroine’s fantasy projection. Then, long after Gravity’s Rainbow(1973), his major effort, came Vineland (1990), set in 1984 but also looking backward to the hippie idealism of the late ’60s, and pondering, with grief and a genuine sense of urgency, what might have happened to it.

Now, after Mason & Dixon (1997) and Against the Day (2006), one finds more laid-back disillusionment in Inherent Vice — a gumshoe pastiche set in surfside L.A. in 1970. It’s a kind of southerly remake of Vineland (which was set mainly in Northern California) featuring similar showdowns between freaks and cops and further evidence of defections and betrayals but played, this time, more for cheap thrills than for any fresh historical insights. And replacing Crying‘s WASTE is a more generic Great Whatsit called The Golden Fang, a boat that might be a tax dodge set up by dentists.

It’s worth returning to that jacket blurb in order to interrogate it. Is the new book lively? Up to a point, but not compared with its predecessors. On the other hand, if you’re undemanding, this plainly passes muster as beach reading. And is Pynchon working in an unaccustomed genre? Not if one considers the various gumshoe elements found among the many genre pastiches in his other novels (which always served as seasoning, never as the main course). But Inherent Vice is certainly a classic illustration of something or other, such as (maybe) giving up the project of being a serious novelist, albeit without offending anyone except for a few longtime and die-hard fans like me. And at least it’s a yarn, which Pynchon has never quite managed before.

For once, this flouter of reader expectations is playing by most of the genre rules. The hero, Larry “Doc” Sportello, is a short, 29-year-old private investigator whose taste for weed seems to exceed Philip Marlowe’s liking for booze. He has a home near Gordita Beach (a location already cited in Vineland — apparently suggested by Manhattan Beach, where Pynchon wrote much of Gravity’s Rainbow) and an office near LAX. Doc’s powers of detection are variable, often depending on how much he’s been smoking, and his sense of mission is generally so lax that this periodically becomes an excuse for more digressions.

The year is 1970, after Charles Manson gets arrested but before he comes to trial: In other words, the utopian dreams of the counterculture are already in their death throes. Everyone, cops and stoned freaks alike, seems to be working both sides of the street — or at least wanting or trying to. Doc is asked to spy for the cops in exchange for grass, and his own girlfriend, a deputy DA, casually sells him at one point to the feds. “Life in psychedelic-sixties L.A. offered more cautionary arguments than you could wave a joint at against too much trust, and the seventies were looking no more promising.” This is Doc’s conclusion, though as the book advances, more and more of these jaundiced reflections about everyone’s inner corruption seem to come from the author.

The hero may be living, emotionally, inside a sort of amiable deep freeze, but Pynchon still takes pains to furnish most of the usual mystery staples. There’s everything from a glamorous ingénue in trouble (Doc’s ex) in the opening scene to an eventual plot resolution, of sorts, with carefully contrived (if implausible) narrow escapes and belated sexual rewards for hapless Doc — long after we’ve given up hope of him ever getting laid.

There are also plenty of funny hard-boiled rejoinders (“You are one crazy white motherfucker.” “How can you tell?” “I counted.”), plus frequent authorial annotations about weather conditions, what cars people are driving, what freeways and freeway exits they’re taking, and especially what kind of reefer they’re smoking (“prerolled Panamanian,” “seedless Hawaiian,” “inexpensive Mexican produce,” “Asian indica, heavily aromatic”) that more or less match Raymond Chandler’s accounts of all the lousy meals Marlowe ate.

It seems as though Pynchon is trying to make it up to all the beach-blanket readers who cried foul when he didn’t produce conventional denouements in his other novels. The resulting lack of depth (emotional as well as intellectual) is palpable — and, to judge by pre-publication reviews, possibly salable, too. But I’m not convinced that he’s found his element. Even if he’s understandably reacting against some of the knee-jerk paranoia of The Crying of Lot 49 and the nostalgia of Vineland, most of the hard-won wisdom offered here as a corrective feels shopworn. Vineland already expressed much of the same skepticism about the political utility of hippie passivity — and did it better.

Even by the standards of his elected genre, Pynchon’s success is debatable. I was waiting and hoping for real-estate tycoon Mickey Wolfmann — the current boyfriend of Doc’s ex, seemingly a capitalist villain whose disappearance sparks most of the action — to make a dramatic entrance, like Harry Lime in The Third Man, but when he finally does turn up briefly, he’s barely present at all. Some other characters, such as Doc’s relatives (his savvy real-estate guru Aunt Reet and his loving parents, Elmina and Leo), provide excellent cameos but don’t grow into anything more substantial. Doc himself is dumber than other Pynchon heroes. This is a guy who’s convinced that Sherlock Holmes was a real person and whose musical taste runs to surfer-rock.

Despite some unexpected flickers of warmth the author shows toward the lead cop, Bigfoot Bjornsen — perhaps the best-educated person in the book as well as the most sarcastic — and more than flickers toward a couple of wistful ex-junkies, most of the secondary characters figure as little more than the butts of various stoned-doper jokes.

All of Pynchon’s previous books dared to propose new ways of thinking about both the past and the present, often by combining the two into surreal palimpsests and sometimes by shaping everything into formal patterns involving either narrative trajectories (the shape of a V in V., the thrust of a rocket in Gravity’s Rainbow) or human entanglements (the interwoven lives and families in both Vineland and Against the Day). As Edward Mendelson, Pynchon’s most perceptive critic, has noted, there are often prophecies of the future set in the past (meaning the novel’s present), and one can spot some of these here: early intimations of computer culture, real estate, and credit scams. But none of this is exactly news in 2009.

Most of the Pynchon-ian hallmarks are present — acronyms (“LSD Investigations” on the door of Doc’s office stands for “Location, Surveillance, Detection”), anagram nicknames (“El Drano” for Leonard, a heroin dealer), song lyrics (less funny this time) — but they sometimes feel as obligatory as the catalogs of car models. And the opening of Chapter 4 is the epitome of tired, dumbed-down prose: “On certain days, driving into Santa Monica was like having hallucinations without going to all the trouble of acquiring and then taking a particular drug, although some days, for sure, any drug was preferable to driving into Santa Monica.”

By the same token, one could still theoretically argue that any Pynchon novel is preferable to none, and Inherent Vice, which seems almost preternaturally aware of its own limitations (as suggested by its title), still offers us the pleasure of his company. Yet, to paraphrase that jacket copy: If you can remember the ’60s and the early ’70s, and what emerged from Pynchon’s head in those days, you can’t forget those books—and then you … or, wait … It’s impossible not to be disappointed that the Renaissance intellectual, who blended populist aspirations with the wildest of fancies and cast unnervingly instructive light on our times, has settled for such a modest diversion.