But little in this episodic freakout hits the target quite so well as the wild end credits sequence, a dance number set in a suburban A&P supermarket, in which the entire ensemble boogie in aisles stacked with products, accompanied by an LCD Soundsystem banger called “New Body Rhumba.”

With that ecstatic visual, Baumbach nails a key theme of the book — Americans seeking solace from their mortality in consumerism.

The 1984 novel is a postmodern satire of encroaching disquiet and cacophonous chaos that — particularly in its depiction of environmental catastrophe and human-made disasters — now seems even less like epochal paranoia than it did at the time. But although it’s crammed with characters and events, it’s also fundamentally a careening clown car of ideas, which is probably why it’s long been considered unfilmable.

The family of Jack Gladney (Adam Driver) and his wife Babette (Greta Gerwig), each on fourth marriage and raising the children of previous unions, is bth ,arge and eccentric.

Jack’s analytically inclined teenage son Heinrich (Sam Nivola) and sensitive younger daughter Steffie (May Nivola).

Then there’s Babette’s Denise (Raffey Cassidy), 11, monitoring her mother’s neurotic behavior, and the son, 6, they had together, Wilder (twins Henry and Dean Moore).

Also sharp is the satirical take on an academic milieu, the playfully named College-on-the-Hill, a liberal arts institution that here feels like upstate New York. Jack founded the department of Hitler Studies and is embarrassed that despite it being a course requirement, he never learned German so is hastily taking lessons ahead of a conference.

Murray opens the film with a class on the car crash in Hollywood movies, rhapsodizing about the “secular optimism and self-celebration” delivered in big-screen auto collisions, each one more spectacular than the last. He enthuses over footage of mangled metal and flaming wreckage, admiring a carefree, lighthearted quality that foreign movies could never approach. One of the standout set-pieces of this enjoyable early section is an impromptu joint lecture in which Jack lends his campus rock-star mystique to Murray’s class as they parallel the lives of two mythic figures, Hitler and Elvis Presley, respectively.

At home, Jack and Babette both fret about being the first to die, left to face the abyss alone. Death is a hot topic in the ramshackle house, with the kids rushing to the TV to watch news coverage of a plane crash.

It’s when Baumbach’s script shifts from wry situational observation into more concrete plot incident that the material starts showing its age and the literary roots become cumbersome.

Corresponding to the novel, the second part kicks off when an oil tanker crashes into a freight train in the nearby area, causing a chemical spill upgraded in news reports from a feathery plume to a black billowing cloud to an “Airborne Toxic Event,” which gives the section its title.

An evacuation order triggers panic, which is amplified in Jack when he’s directly exposed to the cloud while pumping gas. It doesn’t help that he’s told to sit tight for 15 years to gauge the health risk.

There are fun touches, like science geek Heinrich gaining social confidence as he regales the crowd of evacuees at a camp with his insights.

But the film becomes steadily less involving — and more grating in its quirks — as it explores both the ecological and emotional fallout of the chemical spill.

The power of violence and terror to reunite families in troubled times seems a ripe notion for satire, as does the American dependence on pharmaceuticals for comfort and the long reach of eco-messes in our lives. But the movie’s manic machinations become less connected to any tangible contemporary reality.

Even rollicking sequences like Jack and brood speeding away from danger in the family station wagon, temporarily set adrift on a river, don’t build much comic momentum.

The feeling remains that Baumbach is more in command with character-driven material than with this kind of absurdist plotting.

Driver makes amusing use of his outsize physical presence by swooping around the College-on-the-Hill campus wearing his academic gown like a vampire’s cape.

Gerwig, sporting a mop of tight curls, fades away much like her character, who spends stretches of the movie staring out a window in sweats, lost in anxiety.

The kids remain more captivating, with Sam and May Nivola (children of Alessandro Nivola and Emily Mortimer) making lively impressions, while Cassidy is an appealingly bossy presence, and the most responsible figure in the house.

“We are fragile creatures surrounded by a world of hostile facts,” says Murray late in the action, articulating a thesis about learning to shut out that world, however temporarily.

More apropos is Jack’s comment near the start: “Let’s enjoy these aimless days while we can.”

Only in the closing supermarket dance explosion does that exhortation become truly infectious. Despite the movie’s inconsistency, at least it sends you out on a high note.

Credits