The team tries to deal with the possibility that Leo will not get better; a new mutant captures Raphael.

When the Turtles return to the city to search for Splinter, they discover that the city has been overrun with Kraang.

The Shredder kidnaps and experiments on the Mighty Mutanimals.

Michelangelo and Casey become friends with Mondo Gecko, a radical, skateboarding, reptilian teenager.