According to the Cannes Film Festival's website, "Clouds of Sils Maria" tells the story of Maria Enders (Juliette Binoche) who is asked to perform in a revival of the play that made her famous twenty years ago.
But back then she played the role of Sigrid, an alluring young girl who disarms and eventually drives her boss Helena to suicide.
Now she is being asked to step into the other role, that of the older Helena.
A young Hollywood starlet with a penchant for scandal is to take on the role of Sigrid (Chloë Grace Moretz), and Maria finds herself on the other side of the mirror, face to face with an ambiguously charming woman who is, in essence, an unsettling reflection of herself.
She departs with her young assistant Valentine (Kristen Stewart) to rehearse in Sils Maria, a remote region of the Alps, and tries to seduce her.