Blackfish, purchased by CNN at Sundance, is the story of a captive performing Orca connected to the deaths of several people and premieres on Thursday at 9 PM ET. The film traces the 39-year history of killer whales in captivity leading up to a 2010 incident in which an experienced Sea World trainer was killed by the 12,000-pound orca, Tilikum, who had previously been associated with the deaths of two other trainers. Orcas are thought to be one of the most intelligent species in the animal kingdom, and the film details the consequences of holding them captive to perform for the amusement of spectators, while subjecting them, CNN said, to a “much darker existence when the show is over.” Pandora’s Promise features the rift within the environmental movement created when some environmental experts take a journey of “defection” in the debate over climate change, and now support nuclear energy; it premieres November 7 at 9 PM ET. Oscar-nominated director Robert Stone examines how fears of “nukes” may have extended the era of fossil fuels, perilously accelerating the pace of climate change as the global demand for energy soars, particularly in the developing world, and takes viewers inside the exclusion zone around Fukushima and into the area of the Chernobyl nuclear power plant.

Related: Hot Trailer: ‘Blackfish’