Fifteen-year-old Jackson is different from the other children at the foundling hospital. Scales sometimes cover his arms. Tentacles coil just below his skin. Despite this Jackson tries to fit in with the other children. He tries to be normal for Sister Jerome Grace and the priests. But when a woman asks for a boy like him, all that changes. His name is pinned to his jacket and an orphan train whisks him across the country to Macquarie's.

At Macquarie's, Jackson finds a home unlike any he could have imagined. The bronze lions outside the doors eat whomever they deem unfit to enter, the hallways and rooms shift and change at will, and Cressida - the woman who adopted him - assures him he no longer has to hide what he is. But new freedoms hide dark secrets. There are territories, allegiances, and a kraken in the basement that eats shadows.

As Jackson learns more about the new world he's living in and about who he is, he has to decide who he will stand with: Cressida, the woman who gave him a home and a purpose, or Mae, the black-eyed lion tamer with a past as enigmatic as his own. The Kraken Sea is a fast paced adventure full of mystery, fates, and writhing tentacles just below the surface, and in the middle of it all is a boy searching for himself.