PARIS--Take 15 well-known French theatre and film actors, add a classic Greek legend and voila, you have the makings of the latest Cannes offering from French director Alain Resnais.

"Vous N'Avez Encore Rien Vu" (You Ain't Seen Nothin' Yet) is an art-house film within a film that relies heavily on its ensemble cast, whose members include Sabine Azema, Pierre Arditi, Anne Consigny and Lambert...