@27mymy27,
buy your sister this book instead
When Grace was younger she was attacked in her backyard by a pack of wolves. No one in the area knows why the wolves decided to attack or even how she survived an attack that should have killed her. Grace knows the reason that she is still alive today is due to the fact that a certain wolf stood up to the pack and helped her in her time of great need. From that day on Grace has had a very special connection the "her" wolf. She sees the wolf in the woods behind her house every winter, but magically it disappears during the summer. An unexplainable bond between the two has formed.
Six years later, Grace finds out the truth about the mysterious disappearance of the wolf in the summer. The wolves in the back of her house are actually werewolves that change not by the moon cycle but instead by the temperature. When it's hot out they are human but during the colder winter months they are wolves.
After a sting of events Grace finally meets Sam (her wolf) and a beautiful romance forms between the two of them. The only problem is that tensions are high in the city as there was another more public wolf attack and this time the boy that was killed is missing.