Paco, a Peruvian Indian boy, is tired of herding llamas up in the Andes, and wants to be out in the fishing boats with his father. He and his younger sister Pepita decide to sneak off with one of the boats to try and catch El Rayo de Oro, the largest rainbow trout in the lake. El Rayo is so big that when Paco has the fish on the line he is dragged into the water, but he is saved in time by his father. The story is simple, but to a certain extent, and mainly through the names, it is illustrative of its Andean setting. The stylized, brilliantly colored illustrations have employed some of the motifs of Indian design.