Julia Wilkinson

History
In 1958, a Sister Mary Katherine at St. Bonaventure Convent in Milton, Illinois kills two other nuns and then commits suicide. Henry Winchester and Josie Sands are sent by the Men of Letters posing as clergy members from the Office of the Inquisition to investigate possible demonic possession. As a novice, Sister Julia is tasked with showing them the dead nun's room, where Josie recognizes a symbol on the wall as representing the Knights of Hell.

That night, Julia hears a noise and sees the Mother Superior dragging a struggling person. Sister Agnes discovers her and Julia is taken captive and tied to a chair next to two other people. Sister Agnes takes a prisoner into another room, where a moment later a brilliant white light can be seen under the door.

Henry and Josie break in and use holy water to subdue the possessed nuns and start to perform the and exorcism ritual to banish the demons. Julia manages to free herself and hide. Henry tries to exorcise the demon from the Mother Superior, but it has no effect and she knocks him unconscious.

The Mother Superior complains about hunters, but Josie asserts that they are Men of Letters. As Sister Agnes returns, Mother Superior reveals herself to be Abaddon, and decides to possess Henry so that she can infiltrate the Men of Letters. Josie offers herself in Henry's place, and Abaddon possesses her. Abaddon tells Sister Agnes to play dead and continue their work until she hears from Abaddon. She then wakes Henry, telling him they exorcised all the demons.

As Henry and Abaddon, who is using Josie as her meatsuit, leave the convent she admonishes the surviving nuns not to speak of what happened, paying particular attention to Sister Julia who knows her true identity.

Sister Julia left the order soon after.

Present
Aware of the violent attacks happening in Milton, Julia tries to tell the police that demons are behind them, but is not taken seriously. Sam, posing as an FBI agent, overhears, and speaks to her, stunned to find she knows about the Men of Letters and had met his grandfather Henry and Josie Sands, she then relates to him the events of 1958. While investigating Sam recognizes the name of the convent, now deserted, as being the name on the van connected to one of the people affected in the town. He goes to the convent and discovers that Sister Agnes is harvesting human souls for Abaddon to turn into her own demonic army in order to take over Hell. She attacks him, but Sam is able to start an exorcism ritual, but ultimately is forced to kill her using Ruby's knife.

Afterwards, Sam thanks Julia for her help and asks her why she didn't warn his grandfather that Josie had been possessed by Abaddon. Julia says that nothing had prepared her for facing true evil, and that she was still ashamed that she had been too afraid to speak up.