Nottingham, 1827.Mary Reddish, a young housemaid unjustly committed after defying her employer's advances, must navigate the brutal treatments of the county asylum while trying to prove her sanity. Meanwhile, Ann and Thomas Morris, the asylum's matron and director, struggle to uphold humane practices against outdated medical methods that haunt the institution.

As Mary forms an unlikely alliance with a fellow patient, she finds herself at the centre of a battle between compassion and cruelty that will determine the course of her life - and the future of the asylum itself.