Some time later, Katie, now referring to herself as Maud, has become a devout Roman Catholic and is working as a private palliative care nurse in an English seaside town. She is assigned to care for Amanda, a dancer and choreographer from the U.S. who is terminally ill with stage four lymphoma. Amanda is embittered by her fate and confesses to Maud that she fears the oblivion of death. Maud comes to believe that God has tasked her with saving the atheist Amanda’s soul. Maud reveals to Amanda that she sometimes feels God’s presence and she and Amanda appear to be overcome with ecstasy as they pray together.
Maud becomes suspicious of Amanda’s companion Carol, who visits regularly and whom Amanda pays for sex. She implores Carol to stop visiting as she believes Amanda’s soul is in jeopardy. Carol attends Amanda’s birthday party anyway and in front of Maud, Amanda informs the partygoers that Maud tried to drive Carol away. She mocks the young nurse for trying to save her soul. Maud strikes Amanda and is dismissed from her job.
Believing that God has rejected her, Maud visits a pub to find companionship but is rejected by most of the people she meets. She goes home with a man and during sex, suffers flashbacks of the death of her patient and her attempts at CPR, which causes her to stop. The man rapes her and then, as she is leaving, taunts her by revealing he remembers her hooking up with a friend of his during her hedonistic past.
While out walking, she encounters Amanda’s new nurse and storms off when she realizes that her replacement enjoys a good relationship with Amanda. In her decrepit apartment, Maud begs for a sign from God who appears to tell her to be ready for an act that will demonstrate her faith. Maud interprets a vortex in the clouds as a sign from God.
That night, Maud, dressed in a makeshift robe and wearing rosary beads, enters Amanda’s house after the care nurse leaves. She finds Amanda in bed, weakened. Amanda asks forgiveness for mocking her faith and Maud joyously reminds her of the time they experienced God’s presence. Amanda reveals that she feigned the experience and that God is not real. Maud recoils in horror as a now-demonic Amanda hurls her across the room and mocks her for needing to prove her faith. In a delirious frenzy, Maud stabs Amanda to death.