The personalities of Shredder and Splinter are switched when a device is accidentally activated during a battle between the Turtles and their enemies. As Shredder plans the Turtles' demise and Splinter plans on how to get back to his body, everyone else is clueless.

A robot warrior, known as the Mobile Armored Computerized Combatant (M.A.C.C.), arrives from 400 years in the future in 20th-Century New York. He befriends the Turtles, but Shredder and Krang are looking to bring him to their side, at any means necessary.