This book is the fifth book in a series about the adventures of Nicholas Flamel and others in his world. The characters in this book either want to save the ancient city of Danu Talis, which would mean the destruction of what is the current world, while others want the city to fall as it did in the past in order to save the present world. The battle has begun over Danu Talis, and this battle will continue into the sixth and final book of the series.

The Warlock begins just as Josh, Dee, and Virginia flee from Dee's burning office. Sophie has betrayed Josh, in his eyes, by whipping a creature he had just brought into the world. He thinks she has been corrupted by the Flamels, while she thinks he has been corrupted by Dee. As the story continues, it is clear that Josh is the one who has been corrupted. Dee and Virginia plan to return to Danu Talis to take over the world; Virginia wants power and Dee wants the knowledge taking over Danu Talis would give him. Josh is told that by following them and bringing the Elders back to the world, peace and love would return to the world. By the end, Josh has changed a great deal. He has a much harder and colder look in his eyes. This is due not only to spending time with Dee and Virginia, but also from spending time near the Coward's Blade, Clarent. This sword has a history of corrupting its users.

Sophie, unlike Josh, does not enjoy the power she has. She wishes for life to return to normal, but after spending much of the book with Tsagaglalal, the Flamels, and the other warriors, she finally begins to accept her destiny. Although she agrees to help save the world, she really hopes to save Josh in the process. Throughout her life, she has only truly trusted him. She is not willing to believe like the others that he is a lost cause. Tsagaglalal has foreshadowed that their next meeting will be short and unpleasant. Sophie waits for their next meeting with excitement and, without thinking, grabs Josh's hand and jumps into a dark, silent, scary hole.

The book ends with a huge twist as it is realized that Sophie and Josh's parents are not who the twins think they are. They are the immortal and powerful Isis and Osiris. The next book will continue to exciting saga.