Loooooove this though i think that maybe you are running into the action too fast. make it so that Cassidy doesn't speculate that her deranged sister is kidnapped or whatever until she sees more signs of magic. Then you could have her freak out, maybe while waiting for her friend to come out of a shop at the mall, and sprints the long way home.
@Imaginekta,actually the fact that your stories are fast paced is a really good thing, its just that you need to know when to slow it down. ill help with that as you go on with this story