In Little Seville, a fictional village near Madrid, nine eleven-year-old children, boys and girls, classmates at the same school and teammates in the school's seven-a-side soccer team, Soto Alto, swear never to part and to always play together everywhere. They secretly call themselves "The Soccer Kids" and decide to solve problems and unravel the strange situations that arise. The Inter-School Championship ends, and Soto Alto is at risk of not only being relegated but also being disbanded as a team. The parents' association has stated that if Soto Alto falls to the B division, they will remove soccer from activities and introduce dance lessons. The nine children, namely the seven main players and the two substitutes, decide to do their best to win at least one of the three remaining matches. But just when they seem to be achieving their goal, the referee falls flat on the field and falls asleep. The match is interrupted, and when it resumes after a while with a substitute referee, the game is lost for Soto Alto. The same happens in the second match, so the children, to avoid losing the final, decide to solve the mystery of the sleeping referees. Will they succeed, or will they get into dangerous adventures? Who do they suspect, and what will their investigation reveal?