Elena's been on what the movies call a "roaring rampage of revenge," tearing through mutts in search of Malcolm Danvers, the big bad wolf who beheaded her fiancé, Philip, and kidnapped Logan's ladylove, Rachel.

Malcolm's been marked by Aleister, a powerful male witch who needs Malcolm's blood for something called "the Undoing," a vengeful ritual that will destroy every witch across the world (except Aleister, being the only male witch). To perform the Undoing, Aleister also requires the abilities of Savannah, a powerful young witch whom he manipulates and trains to reach her full potential.

… a mission all the more grave after Elena kills Malcolm and is kidnapped by Aleister.

Elena befriends Savannah, who's being kept in the room next to Elena's cell. Elena warns Savannah of Aleister's evil plans, though Savannah isn't yet powerful enough to break free of Aleister's mind-controlling spell.

As if this isn't enough to deal with, Jeremy finds a new enemy in Eduardo, who's looking to rise in the ranks of the Pack after Jeremy murdered his treasonous Spanish Alpha, Roderigo. Eduardo's plan to murder the Russian alpha, Roman, is uncovered and he flees into the woods, his current whereabouts unknown.

Not to be undone himself, Aleister once again kidnaps Savannah and succeeds in going through with the Undoing. The Witches are slowly but surely dying … and the werewolves will soon be free from their curse, as werewolves were first conjured by witches.

The final battle takes place at The Catacombs, an ancient witches' sanctuary deep below the streets of Boston, where Ruth sacrifices herself to save Elena's life …