Indagaciones por Madrid (+ Audio CD)

Guillermo and Lucía are 15 years old and they live in Madrid. They are best friends and share everything. One day Max, while waiting for Lucía at the cinema, is approached by a stranger who gives him a mysterious envelope. What is in the envelope? Is the stranger really a member of the Spanish Secret Service, as he claims? Guillermo and Lucía turn into detectives and start investigating…