In their underground lair deep beneath the city streets, the Turtles and Master Splinter are suddenly attacked by a horde of Mouser robots!

The Turtles discover the source of the Mouser robots that trashed their old lair: Dr. Baxter Stockman -- a noted technological genius/inventor, who tries to pass off the Mousers as a means to eradicate the city's rat problem.

When April O'Neil wakes up in the Turtle's lair she has major trouble dealing with the reality of four giant talking Turtles and a Zen-master rat. She soon learns of the origin of the Teenage Mutant Ninja Turtles and they realize their common enemy is Baxter Stockman and his army of robotic Mousers.

Raphael is a little cooped up underground with only his brothers and Master Splinter. When Raphael almost clobbers Michelangelo in some brotherly sparring, it's apparent that Raphael needs to get out ... let off a little steam. But when he meets up with Casey Jones, a vigilante erring a little to the right of justice, Raphael must face the reality of his own hothead ways...

When a scientist accidentally unleashes a super-powered Nanotech monster with a childlike mind, it adopts a small-time thief as its father figure, and the mayhem begins!

The Turtles, investigating a strange blackout, discover the Foot Ninja stealing a Japanese ceremonial sword from the Metropolitan Museum of Art.

After Casey Jones makes himself an unwanted guest in the Turtles' lair, Raphael takes him topside for a "breath of fresh air", where they encounter the Foot Tech Ninjas.

On a nightly training run, the Turtles and Casey Jones break up a Purple Dragon robbery. One of the perps is Angel, a girl Casey knows from the neighborhood who's going through her initiation rites to become a Purple Dragon.

The boys have made friends with a group of homeless, and are worried when they start mysteriously disappearing into the night!

Oroku Saki (aka the Shredder) attempts to convince Leonardo that Saki is fighting the good fight ... that he's out there carrying on the great tradition of Bushido and Ninjitsu, and the turtles should stand with him.

Our four turtles stand facing their most formidable foe to date ... the Shredder. Beaten and battle weary, the turtles get separated from one another during the martial arts mayhem and a building collapse!

Believing the Turtles can accomplish so much more for the city, and inspired by iconic superhero Silver Sentry, Michelangelo decides to take a crack at being a superhero.

When Don's examination of some mysterious crystals attracts the attention of a subterranean monster, the Turtles underground exploration unearths a Foot Genetics Lab!

After discovering an abandoned underground Foot Genetics Lab, and being attacked by once-human Digging Creatures, the Turtles assist those very creatures in trying to repair a Force Field.

After befriending the once-human creatures in an abandoned underground Foot Genetics Lab, the Turtles join them on a journey deeper into the earth, where they come upon the ruins of a once-great subterranean city.

With all the turtles living in April's apartment, things are getting a little crazy. But, when Donatello stumbles upon a fantastic monster in the basement, things get crazier.

On a training run Leo is ambushed by a major Foot attack force, including Foot Tech Ninjas, their old enemy Hun, and a new threat: the Foot Elite!

When the Foot Ninja attack April's apartment in force, the Turtles fight against overwhelming odds to get the wounded Leo to safety.

The Turtles, Splinter, Casey and April just barely manage to escape from the explosion that destroys the antique store. They hit the road and hide out at Casey's grandmother's old farmhouse, but Leonardo is badly wounded.

Still recuperating up at Casey's grandmother's farm, the turtles are feeling the sting of boredom. Luckily, a scientist known as the "Monster Hunter" has come to the area searching for a legendary monster...

The Turtles and Splinter continue to fight their way up through the Foot Headquarters skyscraper, facing down three misshapen Mutant Shredder Clones, a hallway of traps, and the Mystic Ninja.

With Stockman showing up in the middle of the final battle between our heroes and the Shredder, everything is thrown into chaos ... so much so that our heroes must join forces with the Shredder and Hun to defeat Stockman.

With Splinter mysteriously vanished, the Turtles are feeling frustrated, not knowing where to start looking. Impatient with strategizing, Raph heads off on his own - and straight into trouble, of the mobster kind!

After the frustrated Turtles exhaust their search for Splinter, their suspicions turn to the Guardians, and the trail soon leads them to a non-descript building, the initials of its company name spelling out "TCRI."

The Turtles successfully infiltrate the mysterious TCRI Building, where they manage to sneak into its inner sanctum, and locate the unconscious Splinter inside a stasis tank.