恶第四季

　　1. Boko Haram Unnatural Selection: The Nigerian government is determined to drive militants from a terrorist group out of the country A new gene-editing method allow scientists to change the genetic traits of plants and animals.
　　2. Escape to Europe Cycle of Terror: Following the refugee trail from the Syrian border to Europe The global reaction to the terrorist attack in Paris impacts the fight against terrorism.
　　3. Right to Die: Exploring the moral, political and personal questions raised by euthanasia.
　　4. Beating Blindness White Collar Weed: Doctors and researchers make incredible strides in the fight against blindness Struggling small-scale marijuana farmers face corporate takeovers as the end of the pot-prohibition nears
　　5. Meathooked End of Water: Examining the environmental harm of industrial meat operations Assessing the depths of the world's water crisis.
　　6. Return to Yemen Church and States: Examining the conflict in Yemen Exploring the ongoing battle for LGBT equal rights in the United States.
　　7. Palestine Now and Viva Cuba Libre: Exploring the lives of young Palestinians today Examining the political thawing of relationships between Cuba and the United States.
　　8. Afghan Women's Rights Floating Armories: Violence and oppression are still a fact of life for women in Afghanistan Private military contractors protect global commerce.
　　9. The Future of Energy: Examining the future of how to make and use energy and how to meet the growing demand as carbon emissions are cut.
　　10. Trump in Dubai China in Africa: The plight of migrant workers in Dubai Examining the increasingly prominent business relationship between China and Africa.
　　11. The Deal City of Lost Children: Exploring the recent Iran deal from both sides Tribes of homeless children live along the tracks in Kolkata, India.
　　12. The End of Polio and Collateral Damage: Health workers put their lives on the line in Pakistan to eradicate polio Examining the devastating effects of unexploded ordnance in Myanmar and Laos.
　　13. State of Surveillance: Shane travels to Moscow to meet with Edward Snowden and discuss government surveillance programs.
　　14. Heroin Crisis New Age of Nukes: The effects of America's Heroin epidemic and the next nuclear arms race.
　　15. Flint Water Crisis Libya on the Brink: Examining the effects of the water crisis in Flint, Mich. In Libya, rival militias fight to save the country.
　　16. Die Trying: Patients and top researchers across the U.S. discuss recent measures taken to tackle ALS Exploring the regulatory hurdles faced by ALS patients and drugmakers.
　　17. Student Debt Fecal Medicine: The correlation between student-loan borrowing and the soaring cost of college tuition A medical revolution involves using stool from a healthy person to treat severe intestinal infections in others.
　　18. The New $pace Race Closing Gitmo: NASA and a growing community of private companies decide to prepare for Mars exploration Ex-detainees reveal what really happens behind the walls of the American prison at Guantanamo Bay, Cuba.