When Shredder plans to create an army of mutants, the Turtles must rely on the help of the Pulverizer, who was recruited into the Foot (to be expendable) and volunteers to gather information on the inside on their behalf. When he agrees to be a test subject for a stolen supply of Kraang Mutagen, the Turtles rescue him, but not before he recklessly gets himself mutated.

Donatello breaks into a secret Kraang detention center in order to rescue Kirby O'Neil, but ends up trapped inside with a deadly prisoner called the Newtralizer.