https://www.businesswire.com/news/home/20201005005831/en
In My Son, when a man’s (McAvoy) only son goes missing, he travels to the town where his ex-wife (Foy) lives in search of answers. To play a man whose life is clouded by mystery, McAvoy will not be given a script or dialogue – as was the case in the French film - the character will only be aware of basic aspects of his story, and will have to improvise and react to each moment as it unfolds. The rest of the cast and crew will be aware of the scenes. Carion directed his original film the same way with his lead star improvising the role.