"El Secreto del Río" by Isabel Ibáñez is a children's book, likely a fantasy novel since Ibáñez is known for works like "Misión Perdida" which have fantasy elements. The user is probably looking for a free EPUB version of this book. But wait, they might not know the exact title in English, so I should consider that possibility. The correct English title might be "The Secret of the River" to check for any translations.