I liked this one. Twins Carolina and Johnny are sent to live with relatives in Mexico for a summer after their father realizes he isn't dealing well with the loss of their mother. The twins have started to notice something funny happening to them at night. It turns out they are naguales, shapeshifters that can turn into a wolf and a leopard, respectively. It is a generational thing, and twin naguales are special and unique. They discover their mother is actually trapped underground, and they are going to have to travel the Aztec underworld to find her.

If you have a kid who is a mythology nut, this is a great addition to that genre. I enjoyed learning a lot about Aztec mythology. I was also grateful for the glossary and definition guide in the back, because I didn't know a lot of the words, having never taken Spanish and not being familiar with Aztec culture. I'll be interested in checking out the second one.