Build a movie plot around this: Who does the girl meet? Some priests
Answer:
An American girl sets out to make a documentary to understand what happened to her mother, who murdered three clergy people but was not convicted due to insanity and was instead sent to a mental hospital in the Vatican City. She hires a camera man and they attend a seminar on exorcism in the Vatican City. She meets some priests who explain that her mother's condition may not be medical, but could well be demonic possession. She witnesses an exorcism with the priests, which is also caught on tape. The priests and the documentary team then decide to carry out an exorcism on her mother, during which they seek to discover whether her mother is actually possessed. It turns out that she was possessed by at least four demons, and during the exorcism there occurs some transference - the migration of the demon from one body to another. Three of them are possessed and soon after they end up dead. It ends abruptly, with a car crash due to the demonic possession of the cameraman, who was driving at the time.