It all started on an ordinary day, when a letter from Antoni Gaudi, the architect of the Sagrada Familia, emerged out of nowhere speaking about a secret that nobody knew. Two children, John and his friend Peter, now try to discover the secret that is hidden in the Holy Family. And they have to hurry, because there are other people who want to discover it first, and these other people carry very bad intentions ... An exciting adventure for 8 -10 year olds.