The Helm of Darkness (War on the Gods, #1)

The Greek gods are real, and they've come back with a vengeance.

Andy and Zoey are two normal teenagers living in the modern day—that is, until they're knocked unconscious in a freak storm sweeping the United States.
When they wake up, the world they know has been tossed away. Their city is in ruins, strange creatures walk the earth, and worst of all, everyone is gone.

They stumble across Diana and Spencer, two kids around their age who possess incredible magical abilities, and who claim to be...