Cassidy and Jay find themselves pulled back into history once again in this second installment of The Agency. This time, the two find themselves flung back to ancient Greece on a mission to save the Greeks at the Battle of Marathon against the mighty Persia Empire. Making matters worse, this time the two find themselves separated. Cassidy must deal with a future Spartan queen is far from accommodating while Jay races from Athens to Sparta with critical information. Can the two once again save history?