Nemesis

S1 E6: For Mark O'Shea, the Timber Rattlesnake is Nemesis. After a bite from a captive snake, he spent nine days in a hospital, close to death. But the Timber Rattlesnake itself is now in danger. That's where Mark aims to confront the species that nearly killed him, and help the scientists who are trying to save it. But the next bite could be fatal.