Mary and Martha follows two women who lose their sons to malaria and join together to raise awareness of the disease. The cast also includes Lux Hanley Jardine and Sam Clafin.

Blethyn's West End credits include Benefactors, Habeas Corpus, and Mrs Warren's Profession and she has appeared on Broadway in 'night, Mother and Absent Friends. Her film work includes A River Runs Through It, Night Train, Little Voice, Saving Grace, and Secrets and Lies, for which she received a Golden Globe Award and an Oscar nomination.

Swank is a two-time Oscar winner for Million Dollar Baby and Boys Don't Cry. Her stage credits include The Miracle Worker.

Mary and Martha is expected to air next year.