Michael C. Hall concludes his journey to the low-lying country of Bangladesh, where rising seas are expected to ultimately submerge 17% of the nation. Conservationist M. Sanjayan returns to further question some of the world’s top climate scientists as they collect key data unlocking the past and future of our planet’s changing climate. His destination: Tupungatito, the northernmost historically active stratovolcano in the southern Andes. Series finale.