No one ever knew Scott McCall had a younger sister, Ashley McCall, since she lives with their Dad. But when their Dad gets a call, telling him that he has a big case which will take a couple of months and has to move to the other side of the country, Ashley moves back to Beacon Hills with their Mum and Scott. Scott tries to keep Ashley out of all the werewolf business but when she meets Derek Hale, she finds out everything and is in the center of it all.