Roman Polanski's Based on a True Story, contrary to its title, isn't: It's a fiction film about a successful author who avoids her past and an eerily obsessive fan who pushes her to write the “hidden book” her previous work seemed to promise. Of course, Polanski's film is also transparently about the director himself—as well as about his co-writer, French filmmaker Olivier Assayas. And there's an almost incredible arrogance to that.
Polanski surrogate Delphine (Emmanuelle Seigner) is enjoying great success with her new autobiographical novel but also burned out from the promo tour. Elle (Eva Green)—whose name, as is often commented on in the film, literally translates to “Her”—is a supposed super-fan who ingratiates herself into Delphine's life as a “good listener” before gradually moving into the author's flat and taking over her work, deleting slanderous Facebook posts, responding to emails, and even attending a face-to-face gig in her place. Elle also impresses on Delphine the importance of “reality” and tries to dissuade her from writing the fictional book she's pitched to her publisher.