Much of Oliver Assayas' Clouds of Sils Maria is a terrific two-hander between successful-but-aging actress Maria (Juliette Binoche) — who has reluctantly agreed to participate in a revival of the play that made her famous 20 years prior, with her original role now assayed by a troubled, tabloid-bait starlet — and her assistant Val (Kristen Stewart), who runs lines with Maria while engaging in occasionally fourth-wall-pushing philosophical debates about innocence versus maturity, what it means to have integrity as a celebrity in modern Hollywood, and everything in between.