Trouble in Three Rivers city?

Jeff Goldblum and his hometown of Pittsburgh, whether it likes it or not, have combined to create a surprising summer delight.

“Pittsburgh� is a witty variation on a Christopher Guest mockumentary that swirls together fiction, reality and an unlikely cast including Goldblum, Ed Begley Jr., Illeana Douglas, Moby, Conan O’Brien and unsuspecting Pittsburghers, all as themselves.

Goldblum, who first contemplated taking advantage of video technology for some sort of personal project about six years ago, says he didn’t want to create a film as mundane or revealing as a journal.

Instead, he and his collaborators ended up with an approach that owes a tip of the hat not only to Guest (“Waiting for Guffman,� “Best in Show�) but also, as Goldblum sees it, to the spontaneity of directors John Cassavetes and Robert Altman.

“It’s not like we’ve discovered a new planet,� Goldblum said in an interview. “But I thought the way we tried to skin it is a little bit different than anybody else. The tone we hit and somehow the way it came together and what we tried to do, I thought, was pretty nifty.�

Making its TV debut Sunday at 10 p.m. on Starz Cinema and out in September on DVD, “Pittsburgh� follows Goldblum, 54, as he takes on the starring role in a Pittsburgh Civic Light Opera production of “The Music Man,� a daring move for an actor known for his acting, not singing and dancing.

The plot of “Pittsburgh� has Goldblum tackling “The Music Man� out of love, both for the venerable musical and for his fiancée, Catherine Wreford, a Canadian actress who must get a job or risk losing her visa.

Why not sell themselves as a package to the trusting folks of Pittsburgh, a hometown boy made good (a Hollywood movie star! “Jurassic Park�! “The Fly�!) and his lovely girlfriend with an impressive voice, thus benefiting both the city and the couple?

And how about roping in friends Begley and Douglas to appear in the show and, helpfully, in Goldblum’s video project?

What could have been a raging exercise in ego or Pittsburgh-bashing turns out to be a winning combination of Goldblum’s sly, offbeat charm and deft improv as the celebrities involved neatly skewer themselves. The civilians escape unscathed.

In a scene in which the story meanders into the life of Douglas and Moby, who are portrayed as a couple, the musician jumps in with abandon. Meeting Goldblum, Moby casually says he hasn’t bothered to see any of Douglas’ work but he is a film buff: “I like amateur porn,� Moby offers as Douglas squirms.

When environmental activist Begley hits up Goldblum to help promote his latest passion -- a (fictional?) portable solar power device -- the pair film a spot in which Goldblum is reluctantly shown hoisting a travel coffee mug bearing the Solar Man logo.

“Get a jolt from a clean volt!� Goldblum dutifully recites. Then he can’t help himself: He asks to do another take, and then another.

“Pittsburgh� also offers the fun of unraveling a puzzle. Unlike Guest’s comedies, some of what happens in “Pittsburgh� is real -- or at least that’s what Goldblum claims.

All evidence considered (including polite reviews), he and Wreford did appear in “The Music Man� in Pittsburgh for two weeks in 2004. Goldblum says he explained away the camera that accompanied them by saying it was for a home video.

But as he picks through instances of truth versus fiction for an interviewer, there’s a sneaking feeling he’s extending the film’s shell game.

Goldblum swears to the following: That he was engaged to Wreford, that she did have immigration worries, that he’s always loved the Meredith Willson play, that the couple presented as his colorful mother and stepfather are, indeed, his colorful mother and stepfather.

The play’s director really did tell musical theater novice Goldblum, not long before “The Music Man� started its two-week run, that (gulp) he was taking his character of Professor Harold Hill completely in the wrong direction.

“A quirky mixture of documentary and improvised fiction, ‘Pittsburgh’ has generated a buzz,� was the diplomatic e-mail reply from Van Kaplan, executive producer for the Pittsburgh Civic Light Opera, when asked for comment on the film.