The five Oscar nominations of 1968 are emblematic of the slow-motion death rattle of the Hollywood gerontocratic establishment, says John Patterson

In the year that the Oscars almost didn't happen, let's now travel back 40 years to the Oscars that were delayed by two days because of the Martin Luther King assassination. The country was exploding in violence, most of it concerning race, yet Sidney Poitier was not nominated for best actor, despite starring in two race-based films nominated for best picture, In the Heat of the Night and Guess Who's Coming to Dinner, and despite being named the box office star of the year by America's exhibitors for these and a third, even bigger success, To Sir With Love.

Sammy Davis Jr performed a ring-a-ding version of the Best Song nominee, Talk to the Animals from Doctor Dolittle, the $20m musical flop whose best picture nomination was widely believed to have been bought by its producer, Arthur P Jacobs, through a succession of lavish steak and martini dinners laid on for the voters of the Hollywood craft guilds. And Bob Hope, as tacky and reactionary as ever, threw in a few tasteless jokes about actors enduring the 48-hour delay "in a crouch", though he evidently thought King's death hadn't warranted any postponement of the ceremony. Asshole.

I'd heard a lot of these stories, but I've never heard them rearranged - updated and often corrected by original research - as deftly as they are in Mark Harris's marvellously detailed and compelling new look at Hollywood in the 1960s, Pictures at a Revolution. Sometimes a great book is all about the simplicity of its premise, and Harris has found a great one: the stories behind the five films nominated for best picture in 1968.

The five noms from that year are emblematic of the slow-motion death rattle of the Hollywood gerontocratic establishment, and its displacement by a disrespectful, often dissident (and, to its pooh-poohers, dishevelled and disreputable) younger generation who came of age not in the silent era, but in an age of television, conformity, affluence, the bomb, McCarthyism, and a long-simmering social restlessness. The nominations drew generational, political and aesthetic battle lines: on one side, Guess Who's Coming to Dinner and Doolittle, each thrombotic and clueless. In the middle somewhere, In the Heat of the Night, whose liberal pieties were behind the times but ahead of the Hollywood curve. And in the opposing camp, manning their ladders and siege-engines, the smart-ass, LA-sceptical transplanted New Yorkers behind Bonnie and Clyde and The Graduate (whose opening line is a pilot's intonation: "We are now beginning our descent into Los Angeles").

Cutting between, say, the equally long gestation periods for Doctor Dolittle and Bonnie and Clyde (from 1962 onwards), as one kind of sclerotic, gargantuan and fundamentally misconceived kind of film-making gives way to another, more European, sardonic, hipper and cheaper kind, Harris offers a nuanced sense of how rise and fall are slow-motion events that happen simultaneously, and that no one knows what's happening to them while it's happening. Forty years on, it all seems so clear. Harris persuasively proves it was no such thing.

In the deep background of his story, studios are being bought by multinational conglomerates, which will one day embrace the post-Jaws business-model; attendance at film schools doubled in the last year; the paternalistic critical establishment embodied by New York Times reviewer Bosley Crowther (who hated Bonnie and Clyde and lost his job over it) was defenestrated by upstarts such as Pauline Kael (who loved it and netted her perch at the New Yorker for doing so). In time, they, with the Nichols and Beattys, became the New Establishment.

And, as best director winner Nichols said in 1968, whenever he was asked what happened to Benjamin Braddock and Elaine Robinson after they got on that bus: "They became their parents." Oh, how the hippies hated that answer.