A reckoning is coming for Devi Lawson... Settling into her new role as the first celestial with demon magic, Devi faces an unwelcome surprise when the shadow arch-demon abruptly returns to the nether realms. The forces of hell are moving, and they don't want a human running around with their power. The problem is, it's getting a bit much for Devi, too. When dead warlocks start showing up with the celestials' mark on their bodies, tensions between the celestials and demons reach a tipping point. Devi's relationship with the arch-demon's son, Nikolas, is just fuel on the fire. The arch-demons are gearing up for an epic showdown. And this time, humanity might not survive it...