In this third installment of The Agency, Cassidy and Jay find themselves traveling back through time to ancient Macedonia. There, the two come face-to-face with a young Alexander the Great, his father, Philip II, and his formidable mother, Olympias, a priestess of Dionysus who has an unfortunate love of snakes. This time, Cassidy and Jay are tasked with ensuring that Philip is assassinated in October of 336 BCE so that Alexander of Macedon can become Alexander the Great. This mission, however, will test Cassidy and Jay in different ways as they grapple with how far they are willing to go to keep history from changing.