I love this book a lot. It is one of my favorite books.It is a mouse called Paulina and her friends, the Thea sisters. Her cousin, Gonzalo, got lost when he was searching for the secret city. It is not really a city, but it is a place where people from long ago had kept treasure in it. Gonzalo's father is dead worried about him. So, Paulina and the Thea sisters search for Gonzalo in Peru, where the Secret city is located. Will the Thea sisters find Gonzalo and find the treasure.