A young lad known as Jack, from the far and tribal north attempts to integrate into the vast and intimidating industrial city of Tistow. With Tistow rapidly heading to war, he finds himself alone and exposed to the city's dark underworld, led by the enigmatic gang leader known only as Loksley.

But Jack has a secret; blessed by the spirit-like Primals he has the ability to assume animal forms, a power that could easily be abused should that knowledge fall into unscrupulous hands. Unsure who to trust and with friends in short supply, Jack must learn quickly to keep his head above the treacherous waters of the River Effra.