The stakes are higher than ever as all parties rush to Arizona to locate the final key holder. A mute young woman named Heidi is waiting for them – and just so happens to have a portal to Hell in her backyard. Nathan and Kaylee, along with the key holders and their enemies, are on a collision course for the final showdown.

Kaylee's power begins to manifest, along with memories from her time as an archangel. She discovers the horrifying reality of her fate. The portal to Hell must be closed from both sides. They key holders must seal it from this plane, and Kaylee must descend into Hell and close it from the other side, which means, an eternity trapped in Hell.

Desperate for a different solution, Kaylee and Nathan form a plan to save her as well as the world. They just have to convince the Devil himself to forego the apocalypse and close the portal.

But if an archangel and the power of Heaven are not enough to defeat evil, what is?