Eileen (Thomasin McKenzie) is a peculiar young woman whose dreary life stretches on toward unending misery. In 1960s Boston, Eileen shuffles between her father’s emotionally haunted home and the prison where she works. When an intoxicating new counsellor, Dr. Rebecca St. John (Anne Hathaway), joins the prison staff, Eileen is taken. Just as the possibility of friendship (or maybe more) takes hold, her newfound confidant entangles her in a shocking crime.