Based on A True Story, starring Eva Green, Emmanuelle Seigner and Vincent Perez, is based on the novel by Delphine de Vigan about a writer who gets involved with an obsessive admirer after the release of her latest book. The script was co-written by Polański and Olivier Assayas. The DoP is Polish cinematographer Paweł Edelman.

The film was shoot at the end of 2016, produced by Wassim Beji via his French company Wy Productions with a budget of 13.6 m EUR. The Polish coproducer Monolith Films applied to the Polish Film Institute for a minority international coproduction grant and received 1 m PLN / 237,000 EUR in 2017.

Based on A True Story will premiere internationally in Cannes and will screen out of competition. The film has already been picked up for North American distribution by Sony Classics, after industry presentations at the 67th Berlinale IFF. The Polish distributor will be Monolith Films.