Break down of main idea

The film starts off outside a mental institute at night. We see a strange looking girl at the gates and then she disappears, we then see a hand in a pool of blood. The main character then wakes up to find it was all a dream, but she is clearly shaken. She then gets ready for the day and leaves the house. On her journey she encounters a friend and talks to her about the dream she had, her friend simply laughs it off and carries on with her journey. We next see the main character on a bus that passes the mental institute that was in her dream. She is both anxious and curious to go and investigate the building. The rest of the movie involves the main character and her friend entering the building and having a confrontation with the strange girl which changes the whole perspective of her life.