A mad professor named Mindbender creates a law-enforcement robot named "LEX" to clean up crime in New York, but LEX ultimately starts arresting numerous innocent people for the smallest infraction. With the other Turtles unreachable, Leonardo must discover his own innate skills to stop this rogue robot before he and Mindbender declare themselves dictators of the city.

Frip the Polarisoid arrives back on Earth with his family for a visit, and must ultimately ask the Turtles for help in reclaiming his camera while helping them stop Krang's latest plan to conquer the city.