El misterio del Día de los Inocentes is the eleventh book in Los Futbolísimos series. It follows a group of young football players who get involved in a new mystery that happens during the “Día de los Inocentes” (April Fools’ Day), when jokes and pranks make everything confusing. As strange and funny events unfold, the team tries to discover what is real and what is part of a prank, using teamwork, humor, and investigation skills while continuing their football adventures.