Like Woody Allen and New York City, Oscar-nominated filmmaker Paul Thomas Anderson seems to understand the strange, sprawling beauty of Los Angeles like no one else. Whether he’s chronicling the world of rich, lonely housewives, game show producers and self-help gurus in Magnolia, murderous oil barons with bowling alleys in their basements in There Will be Blood or the shimmery sunset of the golden age of porn in Boogie Nights, on a deep, cosmic level, Anderson just “gets” L.A. So, when news broke that Anderson would be adapting cult novelist Thomas Pynchon’s trippy, L.A.-set detective yarn Inherent Vice for the big screen it seemed like a match made in film geek heaven. And for all accounts and purposes, it is…for exactly one hour. Then, somewhere around the hour and fifteen minute mark the film takes a hard left turn into crazy town and never recovers.

The worst thing is that up to that point – you’ll know you’ve reached it when Martin Short enters the fray as a drug-addled dentist – Vice is a virtual master class in pulpy, pothead humor perfection with a cast to kill for. Starring Joaquin Phoenix, Josh Brolin, Benecio del Toro, Owen Wilson, Reese Witherspoon, Jena Malone, Katherine Waterston and a host of other top-notch actors playing characters with names like Bigfoot, Jade, Shasta, Coy, Doc and Sauncho, the first hour of Vice has a breezy, live-in quality that captures the blissed-out essence of 1970’s L.A. like only Anderson can.

Sure the story wanders and rambles – Phoenix plays Doc, a bleary-eyed private eye juggling a handful of increasingly complicated cases, at least two women from his past and a wide assortment of readily available recreational drugs – but when the ride is this fun, charming and completely insane you’ll hardly care. Adding to the seductive thrill of it all is the warm, lilting narration of Joanna Newsom’s character, Sortilège, which billows over the action onscreen like the Santa Ana winds in the fall. Heady, exciting, Altmanesque, Vice is Anderson at his witty, warmhearted best and true fans of his work will never want it to end. Until, you know, that hour mark hits and you begin to get the creeping suspicion that all of this beautiful, gauzy window dressing is just that. And that when all is said and done, there might not be any real there, there.

Not having read Pynchon’s original novel, I can’t say for sure that the book peters out midway as well. But knowing Pynchon’s penchant for frustratingly dense storytelling, not to mention Anderson’s fanboy zeal in getting the details right in his adaptation, I’m guessing the book ends just as uneventfully as the movie does. No resolution, no answers, not even a real ending. It’s like a great inflight meal with a lousy desert. Unsatisfying in the extreme.

So, rather than turn against the film and actively “hate watch” the second half of the movie (like I did) I suggest you simply turn it off. Read a book, start another movie, check your email, whatever it takes to keep that first glorious hour of Vice’s goofy grandeur fresh on your palate. And if that doesn’t work, or you find yourself on a long-haul flight with time to burn, watch the whole movie and then quickly watch it again to see if it gets better on second viewing. Hey, it worked on The Master.

You can currently watch some (or all!) of Inherent Vice on select American, Lufthansa and Qantas flights worldwide. Vice is also available via streaming on Google Play, VUDU and Amazon Instant Video.