According to Variety, L.A.-based Relativity Media will finance Ewan McGregor comedy The Great Pretender, with Arclight Films handling international sales.

The $18 million pic, written and directed by Peter Capaldi, starts shooting next January in London.

McGregor, fresh from his sell-out West End run in "Guys and Dolls," will play four roles in two time settings -- 1938 and 1745.

The script concerns two ambitious producers in the 1930s who hire the hell-raising Hollywood legend Leslie Grangely to play Bonnie Prince Charlie in a movie about Scotland's Jacobite Rebellion in the 18th century.

But when Grangely hits the bottle and disappears, they trick an unassuming extra with an uncanny likeness to the star to fill his shoes.

McGregor plays Grangely and the extra, as well as the two characters they play in the film-within-a-film -- Bonnie Prince Charlie, dubbed the "Great Pretender," and the double used by the prince to confuse his enemies.

Richard Holmes and Ron Fogelman of London-based Gruber Films are producing the pic.