Isaac wakes up with amnesia but is rescued from the Alpha pack by a mystery girl. Jackson has moved to London. Allison and her father have quit being werewolf hunters, and Scott is working on being a better person. Derek has been looking for Boyd and Erica, who were captured by the Alpha pack. Something eerie is causing the animals of Beacon Hills to go insane, and Dr. Deaton concludes that the animals are killing themselves intentionally. Derek gives Scott the tattoo he has been wanting to get, and explains about the Alpha pack's leader Deucalion, who is blind but the strongest and most lethal.