It’s not so much a performance as an impersonation, but Christian McKay does an extraordinary job of channeling the literally mercurial young Orson Welles at the beginning of his post-federally sponsored Broadway career in this fanciful recreation of the circumstances surrounding his triumphant staging of Shakespeare’s “Julius Caesar” in 1937. “Me and Orson Welles” is a curious project for Richard Linklater—a very conventional period piece from a director who usually works with edgier fare. But if you’re interested in Welles—and what cinephile isn’t?—it’s an amusing trifle. If not, well, there’s always “Dazed and Confused.”

The modernized, spare, heavily edited version of “Caesar” that Welles fashioned for Depression-era audiences also confronted with the rise of new dictators in Europe was the initial production of his newly-formed Mercury Theatre Company. And as Holly Gent Palmo and Vince Palmo, working from Robert Kaplow’s novel portray them, the final days of rehearsal were creatively chaotic and the first performance an overwhelming success.

As is often the case in such stories, the narrative is presented through the eyes of a naïve novice—in this case one Richard Samuels (Zac Efron), a art-loving student who wanders into the company and is abruptly hired by the flamboyant, imperious Welles—at no pay, of course—to take a small role in the play. What follows is the boy’s assimilation into the troupe, which includes such well-known players as womanizer-leading man Joseph Cotton (James Tupper), cynical comic Norman Lloyd (Leo Bill), intense manager John Housman (Eddie Marsan) and full-of-himself George Coulouris (Ben Chaplin).

But there are problems. Though Welles takes Samuels under his wing, even introducing him to his radio work (which largely finances the Mercury), the boy is ultimately nonplussed at the great young man’s cavalier treatment of everyone, especially Sam Leve (Al Weaver), the designer he refuses to give proper credit (just as he would later minimize—at least in the opinion of Pauline Kael—the contribution of Herman Mankiewicz to “Citizen Kane”). Even more distressing to the boy is the casual use Welles makes of all the women in his vicinity even though he’s married—something the youth can tolerate until the star’s grasp extends to Sonja Jones (Claire Danes), the company’s beautiful general factotum whom Richard immediately falls for. But since she’s an ambitious girl willing to make compromises to advance, even though she likes the boy, it’s a good thing that Richard meets another, more suitable girl—frizzy-haired aspiring author Gretta Adler (Zoe Kazan), whom he actually helps get a story accepted by the New Yorker.

Though one has to admire Efron’s decision to bypass teen froth for the role of Richard, it must be admitted that he’s not quite right for the part—so handsome and self-assured that the character’s supposed nervousness never comes through. Still, he’s eager and attractive, as is Danes, who hits the right mixture of sophistication and cheek. Their relationship, however, and the one between Samuels and Adler, really play second fiddle to the material surrounding the colorful Mercury troupe. Tupper, Bill, Marsan and Chaplin might not bear the uncanny resemblance to the figures they’re playing that McKay does to Welles, but they show the right spirit. Linklater directs them all with genuine affection, if not much energy, and he benefits from a strong physical production that captures quite well the ambiance of Depression-era New York even though the picture was shot (very well by Richard Pope in atmospheric widescreen) in London and on the Isle of Man, of all places. Kudos are due production designer Laurence Dorman, art directors Bill Crutcher, David Doran and Stuart Rose, set decorator Richard Roberts and costume designer Nic Ede, as well as Michael J. McEvoy, who provides a jovial score supplemented by pop tunes of the time.

The picture includes substantial excerpts from the finished “Caesar,” and as so often happens in such theatrically-based stories, they don’t register as strongly as was obviously intended. (Even in “The Producers,” the scenes from “Springtime for Hitler” just weren’t as funny as Mel Brooks thought.) But even in those sequences, ultimately the movie’s sparkplug is McKay, who mirrors the young Welles not just in looks but in manner and socks across his combination of blustery showmanship, artistic genius and absolute self-regard. Welles certainly doesn’t come across as an entirely likable person, but he is a genuine force of nature.

“Me and Orson Welles” will appeal mostly to older audiences and especially to buffs who will be fascinated at this portrait, however imaginative, of the young wunderkind who went on to become one of the world’s great filmmakers. For them it will prove an agreeable divertissement, easy to take—and equally easy to forget.