Ruby's world has changed more than she ever could have imagined. She's in love with a powerful Frost King. She's the heir to the Fire Throne. And she may be a Nightblood--the spawn of a vengeful deity hellbent on releasing an imprisoned army of shadowy wraiths. Once freed, these beasts will roam the earth, devouring the spirits of every last person until he or she is nothing but an empty husk.

Ruby is able to control the shadows to a degree, even hosting one in her own body. But will this tenuous connection--which threatens to consume her--be enough to hold the beasts back? With time running out, she must bring Frostbloods and Firebloods together to make a stand against an immortal foe more deadly than any she's faced. And the price of peace may be her very life.

In this heart-pounding finale of Elly Blake's gorgeously written and action-packed Frostblood Saga, the fate of Frostbloods, Firebloods, and all of humanity is at stake.