In a freak accident, four pet turtles are exposed to a Mutagenic substance in the New York City sewers, morphing them into human-sized bipedal sentient creatures who are named for Renaissance artists and subsequently trained in the art of Ninjutsu by Master Splinter, a mutant rat transformed by the same incident. Aided by their human allies April O'Neil and Casey Jones, The Turtles secretly protect New York from the machinations of the Foot Clan, a power-hungry clan of ninja led by The Shredder, who has a personal vendetta against Splinter.
