Rebecca Miller’s upcoming biographical film, Moonsong: A Life In Seven Verses, has expanded its cast with several prominent actors, including Josh Hartnett, Emma Thompson, Sally Hawkins, Danny Huston, Robert Aramayo and Chloe Pirrie. They will join previously announced stars Elle Fanning and Julianne Moore in the project, which is scheduled to begin filming in May 2027.

Fanning will portray Margaret Wise Brown, the celebrated American children’s author behind classics such as Goodnight Moon and The Runaway Bunny. Moore will play poet Michael Strange, while Hartnett will portray socialite William “Big Bill” Gaston. The film is set in 1930s New York and explores Brown’s development as a writer, her unconventional approach to children’s literature and her relationships with artists and educators.

The story will also examine Brown’s complicated personal life, including her passionate relationships with Gaston and Strange, and how these experiences influenced her artistic development. Her books have sold more than 300 million copies worldwide and been translated into more than 25 languages.

Miller is directing the film and wrote its screenplay, drawing on Leonard S. Marcus’s biography Margaret Wise Brown: Awakened by the Moon. She described Brown as a fascinating and unconventional figure who combined a childlike perspective with considerable professional ambition. Miller also expressed confidence that Fanning’s portrayal could resonate with younger audiences.

The Veterans will introduce the project to international buyers at the American Film Market, presenting a promotional reel and screenplay. The company will handle international sales outside the United States, while CAA Media Finance will represent domestic rights.

The production team includes cinematographer Jarin Blaschke, special effects artist Neal Scanlan, costume designer Malgosia Turzanska and production designer Kim Jennings. Round Films’ Damon Cardasis and Rebecca Miller will produce, with Martin Scorsese serving as executive producer.

The project marks Miller’s ninth feature film and follows her recent documentary series Mr. Scorsese, which received an Emmy Award and other industry honors.