On the positive, the whole lore of the keys is just fascinating, and it is likely the best part of the book. The villain is quite ruthless in his quest for the Omega Key. On the negative, a couple of the kids seem to be getting a bit dumber, especially the sister who, given her newly found lack of fear, is pretty much being indiscreet and reckless. I found that a bit on the irritating side. Compared to the previous volumes, the story seemed to drag a little bit on this volume. The ending, which I will not spoil, does have a nice twist that may lure you into reading the next volume. I will probably pick up the next volume anyhow. But I am not as excited about the series as I was before.