During one of the flash-forwards, we also saw a bunch of flashes of what appeared to be the Pack members in life threatening situation. The only one I remember for sure if Malia being attacked by someone, they hinted it might have been her mother. For a second there I wondered if it was a real book, but once they explained the origin it became clear it wasn't. So Valek is an enemy of The Dread Doctors, not actually one of them. If you are in the US they do have episodes 1 & 2 of the season streaming for free on Hulu, 3-5 on the MTV app and all of the episodes on MTV.com. I was a kind of annoyed that Stiles didn't tell the others about being attacked. I understand he was freaked out by the whole thing, but I didn't really see any reason not to tell them what happened.