The pack this year is warm and well fed, nothing has come in their path, and everything is going smoothly, until something strange and sinister happens- a young wolf pup falls off a ledge. Everyone is shocked to find Thistle injured at the bottom of the cliff, but just pass it off as an accident. Yet Ash, the Alpha Female's apprentice, has seen something he shouldn’t of, he saw some other wolf push Thistle. The wolf was unknown, and after telling the rest of the pack, it turns out that no-one has ever seen the wolf before. Now, with the near-death of Thistle, the pack are determined to work out who this wolf is, or more importantly WHAT it is trying to do to them.