They only come at night, when the Star fades.

Lark Ainsley escapes the Iron Wood to search for her brother, only to find herself captured and imprisoned in an underground metropolis. Powerful magic protects the city of Lethe, providing sanctuary from the Empty Ones, monsters who hunger for human flesh. But this magic comes at a terrible price, and the city lives in fear of their leader Prometheus and his gang of Eagles. Danger lies in the shadows, and Lark must find the light…