|“||David, when she breaks, and believe me, she will, we don't want to let her leave.||”|
— Olivia (to David about Mia)
The group takes a trip to Mia and David's old family cabin to help Mia get over her drug addiction until the discovery of a certain book turns things upside down.
Olivia is the second person of the group to be possessed, after Mia, and the first to die.
She and Eric were both around to experience Mia's first overdose (something not even her own brother was aware of until the cabin trip), and she was the most adamant on forcing Mia to not return home as she feared for her health. She has a background in medicine and is very confident in her treatment abilities, convincing David and the group that Mia was in capable hands with her after the latter crashed a car in the thick bog.
When Mia escapes from the cabin in a vain intent to avoid the demon that was after her, Olivia and David find her curled up by a tree and bring the girl back to the house, were Olivia treats Mia’s wounds and is reluctant to take her to a hospital. After Mia becomes completely possessed and shoot David in the arm, Olivia tries to reach for the gun, but Mia grabs her and begins to vomit red fluid on Olivia’s face. Later, a scared Olivia washes her face and sees her demonic reflection with an open Glasgow smile. Olivia backs away from the mirror and walks to another room where she’s stopped cold in her tracks, and unable to control her muscles, and urinates on herself.
Olivia becomes totally possessed after that and cut's out a chunk of her cheek into what looks like a Glasgow smile. She tries to kill Eric in the bathroom with a broken piece of glass, but he takes a piece of broken toilet and bashes her head in until she no longer moves.
- The first letter of her name "O" along with the first initials of her friends, "D", "E", "M", and "N", form an acrostic spelling of the word DEMON.
- She is a registered nurse.
- She is the only characters who's soul is not saved.
- She is the first of the friends to die.
- Olivia can be seen as a composite of Shelly.