Buffy the Vampire Slayer (Buffy the Vampire Slayer #21)

Anya has been a key figure in Buffy's life ever since she arrived in Sunnydale, but there's more to the demon's mission and mysterious past than anyone knows! * It starts with her secret connection to the Watcher's Council and... the first full appearance of the Slayer who came before Buffy? * And the truth behind Anya connects Buffy(s) - yes, plural - in ways no one ever saw coming...