Question: Extract the answer to the following question from the movie plot. If the question isn't answerable, please output "Can't answer". Question: Who urges Mary to commit all the killings? Title: Don't Go to Sleep Movie plot: The premise of the story is that a father, Phillip (played by Weaver) and mother, Laura (played by Harper) and their two children Kevin and Mary (played by Robins and Ignico, respectively) move out of Los Angeles (as seen in the opening credits) to a house up north in the countryside. Moving in with the family would be their grandmother (played by Gordon), whom nobody in the family other than Laura cared for very much. The family had just suffered the tragedy of losing their oldest daughter Jennifer (played by Cumming) and hope to regroup and start a new life without her. Just as they move into their new home, Mary begins hearing the voice of her dead sister under her bed. Soon enough, Jennifer's ghost begins appearing to Mary in secret. Jennifer hopes to kill off her family as an act of revenge. Immediately after these meetings with Mary, one by one her family members meet twisted fates. Grandma suffers a heart attack from being spooked by Kevin's pet iguana, which was released onto her bed one night, Kevin is thrown off the house roof after retrieving a Frisbee and father Phillip is electrocuted in the bathtub when the radio he is listening to falls into the water. After it is discovered that Mary committed all of the killings (at the urgings of her demonic sister's spirit), she is placed in a mental institution where it is revealed to viewers through a flashback the fate of Jennifer. Riding home from their grandma's house, Kevin convinced Mary to play a prank on their sister, so Kevin tied Jennifer's shoes together. Apparently they were both jealous of the favoritism their sister was receiving as well as her constant bullying. When their car is accidentally struck by a van and begins to spark, all except Jennifer are able to get out of the car. Jennifer begs for help but Mary simply closes the car door, keeping Jennifer in the car and unable to leave. Just as Phillip is about to go back to get her, the car burst into flames. The final scene of the movie is memorable to viewers who have seen the movie in...
Answer:
Her demonic sister's spirit.