CNN anchor Anderson Cooper, CNN's chief medical correspondent, Dr. Sanjay Gupta, and Animal Planet host and wildlife biologist Jeff Corwin take viewers around the globe for a two-part documentary on the threats to the world's environment. Filmed in 13 countries, "Planet in Peril" brings viewers the stories behind the statistics, uncovering places where environmental change is not a theory or a future forecast but a crisis happening in real time.