Baby Reindeer breakout Jessica Gunning is set to play the music icon Cass Elliot in the feature adaptation of “My Mama Cass“, based on the bestselling memoir written by Elliot’s daughter Owen Elliot Kugell.

Novelist and screenwriter Emma Forrest (Namedropper, Thin Skin) is adapting the screenplay.

Veritas Entertainment (A Complete Unknown), led by Peter Jaysen and Alan Gasmer are attached to produce after packaging the project.

Deadline notes, “My Mama Cass is billed as a definitive film on Cass Elliot, centered on her life, legacy, and the mother-daughter bond that shaped them both, rather than a traditional biopic on the Mamas & the Papas member. It’ll explore how, in a musical landscape that was not short on iconoclasts, Elliot was a trailblazer.  But her true power was that she took things the world didn’t want to give her…a gifted, outspoken singer who refused to be defined by her weight or the men around her, forging a singular career and choosing motherhood on her own terms at a time when the culture wasn’t ready for any of it. The film also highlights Owen’s journey to unravel the truth surrounding her mother’s untimely death — finally laying to rest a long-standing urban legend of how she tragically died at the age of 32.”