Against all odds, Alexa survives the pagan god Hades' clutches and returns to Horizon—but at a steep cost. Part of her soul is missing, and with that, a darkness brews inside her.

When the Legion pairs her with a new petty officer, Milo, a mysterious angel who seems as annoyed as she is to be teamed together, they head to New York City on a lead and things quickly move from bad to worse.

Hades is angry. Hades wants revenge. Now, as the pagan god's threat grows stronger and plagues the mortal world with evil, Alexa must decide whether to trust the secretive Milo and find a way to come together and defend everything they hold dear—before it's too late...