'Like a complete idiot, I gave him the names of famous Hollywood stars who I thought could play Orson Welles," says Christian McKay, recalling his first conversation with Richard Linklater.

The little-known English stage actor had drawn Linklater's attention when the Austin filmmaker heard about McKay's one-man Welles show in 2007. Linklater had a young-adult novel, Robert Kaplow's Me and Orson Welles, that he planned to turn into a movie. The director (Before Sunset, The School of Rock) flew to New York to see McKay's Rosebud: The Lives of Orson Welles, and the two met.

"No way is he going to cast this totally unknown English stage actor, I remember thinking," says McKay. "Not even in my wildest imagination."

And then Linklater had McKay come out to Austin for a screen test ("it was terribly, terribly theatrical," says the actor) and a few days of discussions.

"So we hanged out in Austin, and chatted about film and theater and literature, and his films and Hitchcock's films, Welles' films, everything - and we became friends very quickly.

"And he said, 'Right, well, I'll go and find some stars for you to play with.' "

And, true to his word, he did. McKay, 36, making his feature-film debut, portrays the ambitious, arrogant, twentysomething Welles - mounting his radical Mercury Theatre reinterpretation of Shakespeare's Julius Caesar in 1937 New York. Seen through the eyes of a theater-enamored high school kid (Zac Efron), who wins a small role in the play - and gets to be Welles' gofer and whipping boy, too - the production is absolute madness and chaos. Raging egos, backstage contretemps, money crises, stormy affairs, Welles' dashing off in the middle of rehearsals - it's crazy, and it's sublime. The film, with Ben Chaplin, Claire Danes, Zoe Kazan, and Eddie Marsan, is wonderfully retro in look and feel. An ardent love letter to the magic of the theater, Me and Orson Welles opened Friday at the Ritz at the Bourse.

"I think it's magical to sometimes know how the trick is achieved," says McKay, "and the film lets you behind the scenes."

To immerse himself in Welles for his one-man show, which premiered at the Edinburgh International Fringe Festival in 2004, McKay studied all there was to study - the films, of course, and the letters, books, radio broadcasts, interviews, everything.

He believes that Welles' Caesar, in which the cast threw off togas for dark and austere modern-dress uniforms, "is possibly the most important Shakespearean production in North American theatrical history. . . . When you think 1937, [it] warned of approaching and encroaching fascism and dictatorship, it foretold the Holocaust."

McKay is also not of the opinion that Welles peaked early, that his film career after Citizen Kane and The Magnificent Ambersons was all downhill. In fact, to suggest so to the actor is to get him, well, rather animated.

"That's nonsense," he offers on the phone from New York recently. "That's ridiculous. . . . But I've gotten to be very evangelical about that. If somebody says it was downhill after Kane, then are you saying you didn't like The Ambersons, The Stranger, Lady from Shanghai, MacBeth, Othello, Mr. Arkadian, Touch of Evil, Chimes of Midnight, The Trial? Come on!

"I personally think Chimes of Midnight is a much better film than Citizen Kane," he adds, noting that Kane, while "rightly hailed as genius," has an icy heart. Chimes of Midnight, on the other hand, has a "massive heart," he opines.

"I think there's a different attitude in America about Welles than there is in Britain, in Europe. The other day, somebody said, 'Oh, how sad, he got fat and sold wine.'

"And I always say, well look, he made a lot of money from those wine commercials, and he put that money . . . into his independent filmmaking. Do you know he was selling wine on the radio in the 1930s? So, right at the beginning of his career, as well as at the end. . . . And this is the beginning, the Mercury Theatre was the beginning of his independence. He'd worked for the government and been sacked from the Federal Theater Project . . . and he was doing every radio program and going to NBC and CBS and doing every show he could get on, and pouring all his money back into the Mercury. For me, that's a man of obstinate integrity . . . not a sad man at all."

Shot entirely on soundstages in the United Kingdom - on the Isle of Man, in fact - Me and Orson Welles is a portrait of the artist as a charmer, a genius, a man indifferent to other people's feelings, living in a whirlwind of his own creation, and of creativity.

"He told a lot of myths about himself, and ultimately, the myth destroyed him," says McKay. "Jean Cocteau, who was a great admirer of Welles - I went cold when I read this, but I thought this is perfect - he said, 'I always prefer mythology to history, because history begins in the truth and ends in a lie, and mythology always begins with the lie, but ultimately ends in the truth.'

"And I think that was true of Welles. They went around saying he was profligate - not true. That he was unreliable - totally untrue. That he was slow - he was the most efficient director living in Hollywood at the time, because he had to be. He didn't have the money to mess around."

McKay remembers reading an interview Welles gave to Time magazine back in the 1950s, in which the legendary figure talked about the burden of being Orson Welles. "He said, 'You know, I carry my legend around, my myth around with me.'

"Yeah," says McKay, "but I have to say to him, 'Orson, you started the bloody thing yourself!' I've found many times in my research where the truth of the story was far better than his embellishment."