Edward feels ready to move in with his dad’s girlfriend and her son, Nathan. He might miss having his dad all to himself, but even if things in their new home are a little awkward, living with Nathan isn’t so bad. And Nathan is glad to have found a new guardian for Dew, the young water monster who has been Nathan's responsibility for two years. Now that Nathan is starting to lose his childhood connection to the Holy Beings, Edward will be the one to take over as Dew’s next guardian. But Edward has a lot to learn about taking care of a water monster. And fast. Because Dew’s big sister, the powerful Yitoo Bii’aanii, is coming up to Fourth World to instruct Dew after recovering in the Third World for 160 years. She suspects a monstrous and enormous Enemy from the Hero Twins stories has returned and is stealing water from all of the Navajo Nation. In their search for the Modern Enemy, Nathan, Edward, Dew, and Yitoo must confront their past and their inner selves if they are to save the Fourth World from a devastating disaster.