Task: Question Answering
Input (English): Passage: The film takes place in Minnesota, in 1990. Detective Bruce Kenner investigates the case of John Gray, who admits to sexually abusing his 17-year-old daughter Angela but has no recollection of the abuse. They seek the help of Professor Kenneth Raines to use recovered-memory therapy on John Gray to retrieve his memories, and come to suspect that their colleague Detective George Nesbitt is involved. They detain him but fail to find evidence against him. Detectives suspect a satanic cult is involved because of Angela's testimony, in which Angela says that she was abused by people in masks and someone took pictures of it.
Bruce and Kenneth meet Angela's estranged brother Roy Gray to inquire about why he left the house. Using the regression technique on him, he recalls hooded figures entering his room while he was young. Bruce and Kenneth suspect Roy's grandmother, Rose Gray, has some involvement but find nothing after a search of her house.
Meanwhile, Bruce begins having nightmares involving satanic rituals. Angela tells him that the cult is out to kill her as she has shown her demonic mark to him and that he is in danger as well. She tells him that her mother received miscellaneous calls and saw strange figures staring at her in the street before she met with an accident. Bruce starts to experience the same things and his nightmares increase in intensity. 
Question: What is the name of John Gray's mother?
Output (English): Rose Gray.