Curiosity gets the better of us all, and as I, like the rest of the universe, missed Charlie Sheen’s big screen “comeback” when it was (barely) released in 2013, I took a gander at this one.

The opening on-camera confession/interrogation of Charles Swan III (Sheen) pokes into his character’s obsession “with power and sex,” and the tiny part of his brain that handles “bodily functions and other affairs.”

“Affairs?” The aging, sunglasses-wearing, chain-smoking trainwreck has his interest piqued.

Thus do we begin the flashbacks to the clutter and disasters of his life as seen from inside his head, “A Glimpse Inside the Mind of Charles Swan III.”

And a bigger Cluster-Sheen I could never imagine.

It’s a staggering, under-scripted and shockingly unfunny all-star “rescue” comedy designed to put some of that Tiger Blood on the screen, while Sheen was still kicking and worth a tabloid headline or three.

Long time ago, in other words.

In the title role, Sheen/Swan wanders through the demented fantasies of a celebrated photographer who has philandered away his latest lady love (Kathryn Winnick), with occasional advice aid and advice from his musician-pal (Jason Schwartzman), his accountant (Bill Murray) and and his sister (Oscar winner Patricia Arquette).

“Therapy?”

“I don’t need some guy in wingtips to tell me I’m suffering.”

We revel in a literal dance-at-your-own-funeral sequence with Charles (and a stunt dancer) tripping the light fantastic with assorted exes, a bossa nova duet (Sheen on guitar) with Winnick and Sheen, a dream sequence “Best B.S.” awards ceremony, an imagined “Injun raid” where the warpainted attackers are other Swan exes (Mary Elizabeth Winstead among them), all featuring Sheen and the glories of his omni-present sunglasses and Reagan-Elvis dye job.

It’s a debacle as only a Coppola (Roman Coppola) could fashion.

I’m leaving out the best parts, the endless parade of traveling shots — Swan in his vintage Caddy, or riding in Schwartzman’s vintage Bentley — all set to the quizzical pop of Liam Hayes.

Stay through the charming closing credits — the only place “charm” figures into this — to see who Hayes is.

None of this really ties together, little makes a lick of sense, and Sheen’s movie career plainly ended for a reason. Acting requires more than a smirk.

Roman Coppola wrote and directed this lifeline to the then-death spiraling Sheen, and the fact that Ol’Charlie’s still with us suggests it did him some good to make it.

Not that he’s done anything at all with this second or seventy-fifth chance. Pity they couldn’t have rounded up all these co-stars, from Aubrey Plaza to Dermot Mulroney,  to save, say, Prince.

MPAA Rating: R for language and some nudity

Cast: Charlie Sheen, Jason Schwartzman, Bill Murray, Patricia Arquette, Mary Elizabeth Winstead, Aubrey Plaza, Dermot Mulroney

Credits: Written and directed by Roman Coppola. An A24 release.

Running time: 1:25