In this YA high fantasy, four magical rivals must work together to survive a deadly competition. Perfect for fans of Leigh Bardugo and Gideon the Ninth . Entombed beneath a tooth-filled sky, the world rots. Those who haven't yet decayed inhabit Fourspires Castle, home to arcanists from the four disciplines--blood, bone, stone and botany. But when the king of Fourspires is assassinated, the castle is thrown into chaos. To crown a new ruler, the arcanists and their familiars must kill or be killed in a bloody fight to the top of the Fifth Tower. For the familiars, who are the arcanists' servants and sources of power, this will mean certain death. Nixie, a botanical familiar, discovers that this fate can be avoided if she and familiars from each discipline find four cursed keys and take them to the Fifth Tower themselves. It's a dangerous and deeply illegal quest, and none of them has reason to trust one another. But with just forty-eight hours until the competition begins, four tenuous allies must decide if they can bear to work together long enough to save themselves.