Two years ago, Cassidy's father died in a tragic accident under mysterious circumstances. Ever since, she has struggled to find ways to connect to the world around her.

Now, as Cassidy approaches the end of her eighth grade year, she cannot help but feel a little lost. Cassidy has always loved books and history. But next year, she will begin high school and her mother worries that her math scores will not be strong enough to get into a prestigious magnet school.

Then, one day in April, all that changes. A mysterious substitute teacher arrives at Cassidy's school with a test - a test that, he says, will grant Cassidy access to the magnet schools that will make her mother proud. However, Cassidy quickly discovers this test is about much more than just school.

Suddenly, Cassidy, and her best friend Jay, find themselves enrolling in a mysterious institution: The Agency. The Agency, they are told, has the ability and duty to travel back through time in order to make sure that time and history are not altered, with disastrous consequences.

In their first mission as agents, Cassidy and Jay travel back in time to Ancient Egypt to save Pharaoh Ramesses the Great from a wicked conspiracy led by a shadowy figure: Pa-neck (The Serpent). Along the way, Cassidy and Jay find themselves in a world like none other they have ever known. It is a world of mystics and magic, of princes and slaves, of palace politics and deadly life or death choices. Ultimately, in order to save herself, her best friend, and the greatest pharaoh in Egyptian history, Cassidy must now uncover the secret of who is Pa-neck, who is the serpent? And, along the way, Cassidy might just discover the secret of what happened to her father....