Eduardo and his family live in a small town in Ecuador, not far from the Amazon rainforest. The rainforest is an important part of their lives. Each month Eduardo and his father travel by river from their town to the rainforest. There, using just a basket and a machete, they gather Brazil nuts. They are castaneros and this is how they earn their living.

But the rainforest is not only important to the castaneros; it is home to many exotic species of plants, birds, and mammals, including two playful tamarins that Eduardo has named Tuki and Moka. So although it is difficult work being a castanero, Eduardo looks forward to his visits to the rainforest so he can play with his two friends.

But one night, the peace of the forest is threatened by poachers, animal traffickers who illegally capture and then try to sell some of the birds and animals. Can Eduardo save his friends?