EXCLUSVE : Sarah Gadon ( Alias Grace ), Tom Hughes ( Victoria ), Robert Kazinsky ( Pacific Rim ), and Tamer Hassan ( Layer Cake ) have been set to lead Iron Ribbon , a UK independent feature based on the true story of Polish actress Stanisława “Stasia” Umińska, whose 1920s Paris trial became a landmark crime-of-passion case. Gadon will play Stanisława “Stasia” Umińska, “an ambitious actress at the center of a sensational case that gripped Paris after she was accused of killing her lover, artist Jan Zyznowski — and ultimately acquitted in what became one of the earliest high-profile “mercy killing” trials. Hughes will portray Zyznowski, with Kazinsky playing Donat Guigne ( The Prosecutor ), Hassan set as Arnold Szyfman, and Lee Knight ( Hamlet ) will portray Tuwim. Watch on Deadline Written by Adam Howes ( Foxhole ) and due to be directed by Jarek Marszewski ( Bikini Blue ), with cinematography by Michał Sobociński ( Chopin! Chopin! ), the film is set against the backdrop of Jazz Age Paris.…