Adapted from Sebastian Barry’s award-winning novel of the same name, the story is set against an Ireland besieged by conflict and centres on Roseanne McNulty, a 100-year old woman who has been in a patient at Roscommon Regional Mental Hospital since World War Two. With the hospital near to closing, her caregiver, Dr. Grene, tries to piece together why the woman is there, not knowing Roseanne has been hiding a diary beneath the floorboards in her bedroom.