The Turtles discover for the first time that they are not the weirdest things in New York when they encounter two villains from the Hidden City pursing a cat-like agent. They have their first encounter with Baron Draxum who is making mutants with the help of his Oozesquitos.

In order to save April's job as a party captain at Albearto's Pizzeria, Donnie upgrades the main animatronic of Albearto, only for it to go out of control.

When Donnie's newly-built Turtle Tank goes missing, he and the Turtles must find it. While going after some usual suspects, they are unaware that the Turtle Tank was taken by Splinter, who is additionally invited to "dinner" with Meat Sweats.

After the Turtles stumble across a pizza restaurant in the mystical Undercity while following a Fire Yōkai, Leonardo drags his brothers into a pizza-shaped Maze of Death to obtain the ultimate prize....a free helping to the titular parlor's "world's greatest pizza". But in order to claim it, they will have to contend with the pizza's guardian in the form of the Minotaur who is the maze's assistant manager.