The teams have reached the halfway point of their journey. For the next leg, must choose whether to travel through Bolivia or Chile - both countries with unstable political climates. Sam and Jo decide to break up their travel with regular breaks, while Jen and Rob have an explosive argument when they get caught up in Bolivia's general election. Emon and Jamiul find work in an Argentinian salt mine, and Dom has a health scare that may require him to pull out of the race.

With two teams at the checkpoint – Ilha Grande in Brazil – the remaining teams are engaged in a frantic race to avoid finishing the leg in last place. Dom and Lizzie are on foot running through the jungle, whilst Jo and Sam are paddling furiously in a canoe across the bay. It is a nail-biting ending, and the siblings just manage to edge out their rivals and sign into the book.