If you haven't read Everlost, then you probably shouldn't read this review. But more importantly, don't read the synopsis of this book (Everwild) on Amazon as it gives away an important plot point that the book doesn't reveal until at least the 65% mark.
Everlost is populated by children who died and didn't find their way to the light. They are basically ghosts, who can't be seen or interact with the living world (with one interesting exception). Places (dead spots) and things also cross to Everlost, but only those that are truly loved by someone. The children in Everlost are called Afterlights, because they have a glow about them. Afterlights will sink to the center of the earth if they stand in one place for too long, unless they are on a dead spot. In the first book, we learn that large dead spots are rare, but can be found in places that were considered important to a lot of people, such as the Twin Towers in NYC. In Everwild, Allie, Nick, Mary, and Mikey continue their journeys, although their paths have changed. Some secrets have already been discovered about Everlost, but still more questions remain unanswered.
Shusterman is a magnificient writer and I love losing myself in his worlds. There is no black or white, no flat good and evil. The "good" characters make mistakes or wrong choices, and the "evil" characters have motives that might have started out as good. There is a constant struggle within each character to understand their own feelings and deal with all the crazinees Everlost throws at them. Over the course of this novel, all of the characters (even the secondary ones) develop, grow, and change. There is an overarching theme of "how do we stop the evil trying to destroy the world" and yet each character has their own feelings, hopes, and dreams to deal with.
The instant I finished listening to this book, I began the next (and final) book in the series. This shouldn't be a surprise considering my similar reaction to the first Shusterman series I read (Unwind).
I'm recommending this book to grades 7 and up. Some of the actions of the characters are a bit callous in their disregard for the living world, but there are also beautiful parts that stuck with me. Fans of the Delirium or Divergent series will enjoy this one.