Catherine (Gwyneth Paltrow) is a 27-year-old grieving after the loss of her father (Anthony Hopkins), a genius mathematician whose mind gradually deteriorated from mental illness. With her sister, Claire (Hope Davis), urging Catherine to leave their family home, and an ambitious student (Jake Gyllenhaal) searching through her father's notes, Catherine struggles to keep her composure and her sanity in this drama adapted from the stage play by David Auburn.