"Lucia, a little girl, loses a tooth, Her parents reassure Lucia that the Hairy Tooth Fairy (a mouse named Perez) will come to her bedroom to collect her tooth, leaving money in its place. A mouse who had been monitoring the situation tells another mouse, who in turn tells another mouse... until the news reaches Perez who lives in a boat in the port along with hundreds of other mice. They receive the teeth that he collects, and then clean, shape and polish them so that they can be transformed into shiny round pearls.

What would normally be a routine trip for the legendary rodent takes an unexpected turn for the worse when heartless, malicious scoundrels kidnap Perez to take his boat and his fortune for themselves. Lucia, with the help of her cousin Ramiro sets out to rescue Perez, thus beginning a fascinating adventure with an outcome that just goes to show that you don't have to be a child to believe."