In 1963, before Pynchon's Inherent Vice and 'Doc' Sportello (Joaquin Phoenix in Paul Thomas Anderson's faithful film version), there was Oedipa Maas in Pynchon's 'The Crying of Lot 49.' Both Doc and Oedipa are investigating strange goings-on in Southern California, and both have developed a well-deserved paranoia about the corruption and violence they are discovering, such as neo-Nazi thugs, unsolved murders, corrupt cops, and powerful real-estate developers who got rich turning SoCal deserts into vast tracts of houses and strip malls. Oedipa really just wants to figure out what is happening to her marriage (to 'Mucho' Maas, a DJ for an underground radio channel in the Bay Area, who is chasing after his young female fans), but an earlier short affair in Mazatlán with Pierce Inverarity, the developer - who just wanted her for sex, sound familiar? - turns into a state-wide investigation when Pierce walks into the ocean one evening and never returns, having named Oedipa as the Executor of his vast estate, and Oedipa soon discovers secret links between some odd engineers at the SoCal Yoyodyne (think Rocketdyne) complex and a 16th Century private postal service with a violent past and a suspicious present (their symbol is a muted bugle horn). Oedipa never does solve the mystery of the private post and its sinister connections with the Yoyodyne group, but she finds something in herself, something beyond her Grad School training in 17th-century English literature, that allows her to soldier on and figure out just enough about these mysterious events to overcome (somewhat) her fear of the nameless dread that pervades her (and everyone else in SoCal's) existence.
There's a dread pervading the 1970 SoCal beach culture, too, part of it's the never-ending Vietnam War and the vicious culture war against the youth movement being waged for political purposes by Nixon and his conservative base, and part of it's fear of having your door broken down for smoking pot by Lt. 'Bigfoot' Bjornsen (Josh Brolin); but living at La Playa (the beach) in West LA, Doc and his hip friends get dragged into the murky, scary world of Golden Fang drug dealers and corrupt cops and their hired assassins when Doc is approached by former girlfriend Shasta Fay (the lovely Katherine Waterston) to solve the mystery of the sudden disappearance of her billionaire boyfriend, who Doc eventually finds out has been sequestered by the FBI at a fancy rehab clinic because he was planning to give away free housing to atone for what he now sees was his excessive greed - that must mean he's crazy, right?
With a little help from his friends, Doc solves the mystery of what happened to Shasta Fay's billionaire boyfriend 'Mickey' Wolfmann (Eric Roberts), and narrowly escapes the harsh consequences of messing with the Golden Fang's product. In an ironic twist to the ending, Shasta Fay returns to Doc's arms, but this is the free-love 1970's in SoCal, so with a sly grin she tells Doc "this doesn't mean we're back together"; - but of course they are back together, and all will turn out fine so long as each of them stays true to their hip creed and avoids the corrupting lure of money and greed.