Maria Enders (Juliette Binoche) is a famous French actress. She's on a train to Zurich with her assistant Valentine (Kristen Stewart) to attend a tribute to Wilhelm Melchior, the writer and director responsible for casting her in her first major role back when she was 18. During the train trip, Maria and Valentine learn that Wilhelm has died. They plough on anyway and attend what becomes a memorial for the late writer.
The play that launched Maria's career was called Majola Snake. Maria played an obnoxious young woman named Sigrid who works for a successful middle-aged woman, Helena. Sigrid seduces and then abandons Helena, leaving the older woman a pitiful wreck. Now with the passing of Wilhelm, a new director wants to revive Majola Snake, but this time with Maria as the older woman and a young Hollywood starlet Jo-Ann Ellis (Chloe Grace Moretz) as Sigrid.
Following initial reluctance, Maria agrees to appear in the revival of the play. Her and Valentine hole up in Wilhelm's house in Sils Maria in the Swiss Alps (an area known for its amazing cloud formations, one of which is known as the Majola Snake) to rehearse. The isolation tests Maria and Valentine's relationship – Valentine realises this and half-heartedly attempts to pull away.
Maria soon decides she doesn't really want anything to do with the new play. And after learning more about Jo-Ann, her scandal-prone co-star, Maria gets even colder feet and threatens to pull out. Valentine, thinking the new play will be good for Maria's career, clashes with her boss and the tension between the pair becomes suffocating.
Clouds of Sils Maria was written and directed by Olivier Assayas. The film questions many topics, and is at times unsettling in its refusal to follow every path it creates. Binoche is expert in her portrayal as an aging Maria, and Kristen Stewart gives Valentine a confident and worldly air as a young woman hemmed in by Maria's world. Chloe Grace Moretz's Jo-Ann is abrupt and brilliant at the same time. The glorious backdrop of the Swiss Alps also adds to the eerie discontent between the protagonists. And it is this - the amazingly complex dynamic between Maria and Valentine, and then later between Maria and Jo-Ann - which steals the show.