The new Goodbye Christopher Robin movie will focus on Winnie the Pooh creator A.A. Milne. The new biopic will feature Domhnall Gleeson, who plays Milne, and his son Christopher Robin played by Will Tilston. Margot Robbie also plays Christopher Robin’s mother Daphne in the upcoming movie. The story follows Milne writing about his son and his toys, which later became the famous Winnie the Pooh stories, Entertainment Weekly reported.