When Zack mistooken Annabeth (His actual wife) for her twin sister (Elizaberth) and joins the Darkside (An evil organization) while Elizaberth plays along as Zack's wife, Annabeth and makes Annabeth thinks that Zack died in an accident. Little did Annabeth, Zack and their children knows that Elizabert is from the Darkside and wants to assasinate Zack and his family after the Darkside told Elizaberth that their whole family is working for A.A.I.A (Find it out in the story!)