The Persephone Effect. Gunmetal Olympus, #3

Zeus has been struck down, and Elysium stands on the cusp of destruction. In this tumult, Persephone is wounded but not yet defeated. A presence grows within her that should not be. She has a chance at the goal she's strived toward all along: godhood itself. But just as likely, she could lose everything. Now she must adapt-or drown. Hades, head heavy with her sister's crown, labors to bring the gods to order and keep them united as a killer haunts the city, capable of dispatching mortals and gods alike.
Twin gods Artemis and Apollo grow increasingly erratic, hinting at a scheme that may no longer align them with the survival of Elysium. In the battle for Olympus, the gods must unearth the secrets left behind by their makers-who may not, after all, be entirely gone...