While surfing in the white water rapids of the sewer, Michaelangelo is rescued by Merdude, a half-man/half fish from the lost city of Atlantis. Merdude left Atlantis over 200 years ago in search of others of his kind - it seems that Merdude is the only mutant in the lost city. But now he has lost his way and the Turtles, using Donatello's Porta-Tracker, volunteer to help him find his way back home. Meanwhile, aboard the Technodrome, Krang's computers are picking up some low-level energy readings emanating nearby. With the Technodrome's power reserves at an all time low, Krang thinks it would be prudent to investigate.