After returning Schneider to his hometown, the four brotherly turtles no longer fought together as before, but studied in their favorite fields. The ninja turtles who used to act together have become four "loners"! At this time, a series of strange things happened in New York City. It turned out that industrialist Maximilian J. Wittes intended to conquer New York City, secretly cultivated an army of ancient monsters, coupled with the notorious ninja organization Foot Clan, various dark forces were ready to move in the corners of the city! The turtles are in a state of preparation again! They unite again, ready to attack the dark ones!