OXYGEN opens with Marie Heaton, an anaesthesiologist at the height of her medical career, facing a nightmarish operating room disaster that ends a child's life and launches a tangled malpractice suit. Marie's best friend, colleague and former lover, Joe Hillary, becomes her closest confidante as she twists through depositions, accusations and a remorseful preoccupation with the mother of the dead child.

A quieter crisis is simultaneously unfolding within Marie's family. Her aging father is losing his sight and approaching an awkward dependency on Marie and her sister, Lori. But Lori has taken a more traditional path than Marie, and is busy raising a family. Although she has been estranged from him for decades, the ultimate responsibility for their father's care is falling on Marie. As her carefully structured life begins to shatter, Marie confronts questions of love and betrayal, family bonds, and the price of her own choices. Set against the natural splendour of Seattle, and inside the closed vaults of hospital operating rooms, OXYGENclimaxes in a final twist that is as heartrending as it is redeeming.