Baxter Stockman leads a swarm of flies in an attempt to conquer New York and prove his worth to Shredder and Krang so he can become human again.

Bebop and Rocksteady botch another mutagen experiment, resulting in a giant ice creature who Bebop dubs "Frosty", and Shredder uses this monster to freeze New York solid, preoccupying the Turtles long enough for him to steal thermal explosives needed to melt the Technodrome free from the ice.