Pitch, the Nightmare King, is back—but so are the Guardians. And this time, there's a new Guardian in town. Toothiana, Queen of the Tooth Fairy Armies, is famous for swiping baby teeth in exchange for coins and other small gifts...but there's a whole lot more to her than that. She's fierce and fast and has the uncanny ability to multiply herself into many tiny selves. (How did you think she got to all those pillows each night?) And all those teeth she's been collecting? They contain memories. The forgotten memories of childhood. Memories invaluable to the Guardians...as well as Pitch.