Episode Title:
Vengeance is Mine.
Episode Description:
Leo stages a rescue for Karai against Splinter's wishes. While the mission is a success, Karai's knowledge of the truth makes her rush out to take her revenge on Shredder for killing her mother and lying to her for so long, leading to an unexpected turn of events. Because of Shredder's careless actions, Karai inadvertently falls into a vat of mutagen, transforming her into a mindless albino horned viper when Shredder originally planned to have the Turtles' fall in the mutagen instead. The battle ends with Stockman's lab burning down due to a fire setting during the battle. The turtles, Splinter, Stockman, Shredder and Tiger Claw escape and Karai disappears. The Turtles (particularly Leo) and Splinter are saddened by what happened and return home. Karai appears on a nearby rooftop, where it is revealed that she has partial control over her mutation, able to partially remain in human and snake form.
