Nina and her twin sister, Artemis, are far from normal. It's hard to be when you grow up at the Watcher's Academy, which is a bit different from your average boarding school. Here teens are trained as guides for Slayers — girls gifted with supernatural strength to fight the forces of darkness. But while Nina's mother is a prominent member of the Watcher's Council, Nina has never embraced the violent Watcher lifestyle. Instead she follows her instincts to heal, carving out a place for herself as the school medic. Until the day Nina's life changes forever. Thanks to Buffy, the famous (and infamous) Slayer that Nina's father died protecting, Nina is not only the newest Chosen One — she's the last Slayer, ever. Period. As Nina hones her skills with her Watcher-in-training, Leo, there's plenty to keep her occupied: a monster fighting ring, a demon who eats happiness, a shadowy figure that keeps popping up in Nina's dreams… But it's not until bodies start turning up that Nina's new powers will truly be tested — because someone she loves might be next.
Now that Nina has turned the Watcher's Castle into a utopia for hurt and lonely demons, she's still waiting for the utopia part to kick in. With her sister Artemis gone and only a few people remaining at the castle — including her still-distant mother — Nina has her hands full. Plus, though she gained back her Slayer powers from Leo, they're not feeling quite right after being held by the seriously evil succubus Eve, a.k.a. fake Watcher's Council member and Leo's mom. And while Nina is dealing with the darkness inside, there's also a new threat on the outside, portended by an odd triangle symbol that seems to be popping up everywhere, in connection with Sean's demon drug ring as well as someone a bit closer to home. Because one near-apocalypse just isn't enough, right?