Show #78 (season 5, edition 24)

Debut: FRIDAY, SEPT. 8 (7:30-8:00 p.m. ET/PT)

"Dirty Oil": Nigeria is Africa's largest oil producer, but the billions of dollars it generates have not trickled down to the majority of the population. This disparity has led to rampant oil theft and large-scale attacks on oil infrastructure by locals, who vow to fight until the government allows them to profit through oil jobs and urban development. For a time, the government listened to this plea and paid militants through an amnesty program that curbed the violence. But in 2016, a new administration terminated those contracts and suspended the payouts, leading to a resurgence of militancy and oil theft. Correspondent Gianna Toboni heads to the heart of Nigeria's oil production to witness firsthand the fight of the Niger Delta youth.

"Rebuilding Our Reefs": The world has lost 50% of its coral reefs over the last 30 years, and there's a consensus among marine biologists that climate change will continue to make things worse. Coral reefs are the foundation of some of the most productive ecosystems on earth, providing food, resources and costal protection for more than 500 million people. If nothing is done to stop their deterioration, more than 90% of the world's reefs could be gone by 2050. Correspondent Ben Anderson travels across the world's oceans to see what a few small teams of scientists are doing to keep these vital structures alive.