After taking part in an initiation rite on his first crossing of the Equator, Darwin reaches South America. There he finds the wonders of the Brazilian rainforest. During a stay in Rio de Janeiro he is confronted by the horrors of slavery.

After facing the fearful gales of Cape Horn the Beagle turned north into the quieter waters of Tierra del Fuego. On board Captain FitzRoy had three Indians, whom he planned to return to their homeland to found a Christian colony. But from the start, Darwin was filled with misgivings about the success of the experiment.

In September 1833 Darwin set out to cross the Argentine pampas, heading for Buenos Aires. Immediately he found himself in the midst of a bitter struggle between the local Indians and the forces of General Rosas, who were engaged in a policy of extermination.