Burning Shadow

This is the second book in the Gods and Warriors series by Michelle Paver. It is preceded by The Outsiders and followed by The Eye Of The Falcon.

Synopsis
While searching for his kidnapped sister, Outsider Hylas takes a dangerous detour when he’s captured as a slave and sent to the copper mines of Thalakrea. Hylas faces brutal overseers and lethal cave-ins while evading his enemies, the Crows. With the aid of an orphaned lion cub and his friend Pirra, Hylas must escape the mines and shatter the power of the Crows for good. But the prophecy is still at work and Hylas cannot escape its grasp, especially when the anger of the oldest god is awakened.