Exiled, excommunicated, and with a bounty on his head, Athelas is lying low in Seoul for exactly one reason: he has a wedding to attend. Whether or not he's welcome is another matter. Luckily for Athelas, several bodies have turned up with their soft insides gnawed out, whether by magic or Behindkind—and the latest of those bodies is at the very wedding hall he has been staking out. The Behindkind investigators suspect one of Athelas's housemates: YeoWoo, a gumiho with a thirst for revenge and an even greater appetite for soft underbelly than Athelas.

Athelas has always been opposed to having a small possibly cursed Australian boy in the kitchen. When that small boy disappears, however, and Athelas's housekeeper Camellia strongly encourages him to do something about it, he finds himself wavering. YeoWoo wants nothing to do with the disappearing Harrow, cursed or otherwise. Caught up with her own investigation and preparations for revenge, she would prefer her housemates to remain unseen and unheard. Entirely absent is even better. But Athelas and YeoWoo have something in common.

Hot on the tails of the gumiho who slaughtered her family, YeoWoo instead stumbles over the battered and broken body of a merman who knows just a little bit too much about her quarry. It should be simple to keep Marazul both alive and useful, but although YeoWoo is successful in the former, the latter is a different tail. YeoWoo has always taken what she wanted in blood and force. Athelas has always gained what he needed by deception and manipulation. With their usual methods failing at every turn and the investigation swiftly becoming deadly, it's time to make a few changes.

The world Between is full of dangers, shadows, and reflections. Athelas knows the dangers, is one with the shadows—and has finally encountered a reflection that could be just a bit too much like himself for comfort. The house master has come back. Nobody will quite say who he is, or why he owns the house. And to Athelas's growing irritation, no one will talk about the oddly powerful influence the house master seems to have over Camellia.

The Glass Elder wants wishes. Three, to be exact. Athelas wants a way in, and those wishes may well be that way—but giving the Elder what he wants means putting Camellia in harm's way. It also means that YeoWoo will have to choose between trusting Athelas one last time, and taking a bite at suddenly hot revenge that could swiftly go cold if she misses her chance. Now that revenge is within reach of her teeth, will YeoWoo manage to tear out one last, bloody heart? Can Athelas put aside his own ends for long enough to protect all those dearest to him from threats outside—and from himself?