“Youth” is writer-director Paolo Sorrentino’s ode to old age, a reverie on memory and a fantasia on the last thing to go — “desire.”

He gives one last great role to Michael Caine, one more shot at not seeming streetwise to Harvey Keitel and two great scenes to the legendary Jane Fonda.

He reminds us that Rachel Weisz deserved her Oscar, and that even if he doesn’t score one for “Love & Mercy,” Paul Dano is pursuing just the sort of challenging, uncompromising roles that all but guarantee he’ll have one soon enough.

Caine is Fred Ballinger, an 80something conductor/composer who is doing his best to turn down a knighthood from the Queen. Politely.

“Oh no, I’m retired.”

Harvey Keitel is Mick Boyle, Fred’s lifelong friend, a great film director who has five assistants helping him polish his latest script.

Fred and Mick are at a spa in Switzerland, and in quieter moments, each has his alpine hallucination — the leading ladies one helped launch, the music (in cowbells, cattle lowing, birds and the crackle of a candy wrapper ) the other still hears.

Rachel Weisz is Fred’s daughter and assistant, who experiences a marital crisis that involves both men. Paul Dano is a an actor famous for playing a robot, using time at this exclusive resort to prepare for his next role.

And there’s also this morbidly obese South American so famous nobody has to say his name.

“Youth” plays like Sorrentino’s tribute to Fellini, with its langourus leering during nude swims (Miss Universe checks into the resort), its bemused drift into the indignity of a sauna, and the spa’s regimented routine of exercise, check-ups, sunbathing, meals and nightly entertainment. The filmmaker has been leaning toward Federico of late (“The Great Beauty”), pondering old age as he does.

He does this by contrasting the aged beauties of his cast with the far less attractive, but young and supple members of the staff at the spa, and a few jaw-dropping moments with the film’s Miss Universe (Madalina Diana Ghenea).

Ballinger’s vivid nightmares are about women and desire, his daughter’s are about a failed marriage and Mick’s are about a film ending, a “testament” project that cannot find a climax.

Ballinger is famous for music that he regards as trite, if personal. Dano’s actor observes, chats with Fred and mulls the fickle nature of his fame, a guy too good for the role that made him famous, dismissive of all that’s come since, but not so close-minded that he cannot figure that out.

The performances are subtle and sublime, with the exception of Keitel, who very much seems the odd man out here. His line-readings are metallic, stilted. The Cockney Caine can channel a lifetime among the rich and famous and play it posh. Not Keitel. His “street” moments work, his collaboration scenes with young writers and leisure ones rattle and jar. The lines, the entitlement, doesn’t roll off his lips.

But the surprises are rewarding, the irony expressed with the perfect touch of drollery and the climax beautifully handled, even if the film goes on one scene too long past that.

An old rule Sorrentino violates at his peril. If you spend an entire movie building up some beloved or climactic piece of music, you dare not ever show “Mr. Holland’s Opus” or “Mo Better Blues.” It will never live up to your own hype.

 
MPAA Rating: R for graphic nudity, some sexuality, and language

Cast: Michael Caine, Harvey Keitel, Rachel Weisz, Paul Dano, Jane Fonda
Credits: Directed by , script by . A Fox Searchlight release.

Running time: 2:04