Cobrato was a herpetologist who experimented on himself with snake venom, which somehow turned him into a human/snake hybrid. Some time later, six hundred snakes were stolen from the city zoo and the Turtles decide to investigate. During their investigation, the missing snakes capture three of the Turtles, but Leonardo is able to escape. Leonardo was unable to help his brothers because he admits he's afraid of snakes. Soon, it is revealed that the thefts were caused by Cobrato who wants to raise the Earth's temperature to make it more habitable to the snakes.
Leonardo forces himself to confront and conquer his fear of snakes, only to be confronted by a snake mutant. He knocks Cobrato the ground and ties him up. However, Cobrato escaped while Leonardo was in the next room, only to be knocked into a panel, electrocuted, and mysteriously turned back into a human being. He was not pleased with this development, especially since his beloved snakes immediately turned on him.