I have read other books by this author and the mystery is great. Sometimes the characters do not seem to develop as much. In this novel though, the main characters develop and have good quirky personalities. The mystery of the parvo virus is interesting and it makes you wonder what it would have been like if humans could be infected with that special kind. I wonder if the author was thinking of a sort of werewolf kind of deal.
The only part I must say that I dislike is that the teenagers seem to have no parental or adult supervision. Yes, they seem to be very trustworthy and there's only so many modes of transport off the island but it's amazing how much they are able to get away with during each part of the novel. Plus, the kids seem to be a little slow on the uptake about their new powers.
Overall, it was a great book set with intrigue and a little romance. The ending was very interesting too with a few twists.