Leven Thumps and the Ruins of Alder

This is the end of the series and easily the best of the five books.  Leven's character is evident, the narrator becomes an unnamed character, and the ending is at once complete and purposefully incomplete.
Leven's adventure takes a very interesting turn as he battles against unfinished business and eventually fulfills the meaning of his name (you really need to read this book if for no other reason than to learn why he is called Leven).
The greatest part of this story as a whole and this book in particular is that when things are at their darkest there is always hope.  If you learn nothing from this book you should learn that hope is always present.  The unseen character, Fate, really takes Leven, Winter, Geth, Ezra, Dennis, and even Clover for a real ride.  Geth and Winter find themselves without Leven or Clover and the tension rises as they are joined by the Longing, Phoebe, and some other relatively minor characters trying to escape Foo with the Dearth and the rest of the Foovians.  Meanwhile, Leven and Clover, are mysteriously transported to the ancient island of Alder for an even more mysterious task.  For drama, humor, and a happy ending you really need to pick this book up and remember Foo.