Scootaloo has a problem, a very dangerous problem. She has a disease of the mind. In the day she is a normal filly but when she goes to sleep things turn for the worst. A hidden part of her mind, one that wants to kill is awoken. Rainbow Dash is first to put the pieces of the puzzle together but there was no way she was telling anypony. She loves Scoots and isn't going to let anything happen to her. Eventually Scootaloo conditions worsens and she ends up killing an unlucky Cherilee late at night. When this was brought to the attention of the authorities Scootaloo was forced to run from Ponyville leaving everything she loves behind. But Rainbow wasn't going to abandon her beloved Scootaloo that easily. In a touching story that spans across Equestria they will learn what it means to really care for one another and what it means to be sisters even if they really aren't.