This is going to sound crazy - but - somehow the time-shifting, book-jumping, literary detectiving in the last book somehow ramped up in such a way that it didn't wholly strain the bounds of believability. This book pushes that envelope with no ramp at all. Suspend your disbelief and just dive in - because it does not make any sense. But it's a delightful lack of sense. It's kind of like an adult version of Inkheart (that children's book about characters moving in and out of books.)