Isobel Yeung goes to Brazil's Javari Valley, where evangelical missionaries and indigenous tribes are battling over the soul of the Amazon – and the future of Brazil; Matthew Cassel reports on the financial collapse that united Sri Lankans against the country's ruling dynasty.

Alice Hines investigates how inaccurate drug tests could be determining hundreds of thousands of court cases and upending the lives of people around the country; Melissa Chan travels to Taiwan to find out how residents on the island are preparing against mounting threats of an invasion by China.