After winning a free European vacation, the Turtles journey to Paris, France. Meanwhile, Shredder, Rocksteady and Bebop are planning to steal metal from the Eiffel Tower on Bastille Day in order to power up the Technodrome.

In the Technodrome, Krang works on an oxidizer rocket with enough power to blast the Technodrome to Earth. But something goes wrong, and instead of thrust, the device grows rust! Shredder berates Krang for yet another failed idea, but Krang sees this as a tool of conquest, by threatening to rust all metal on the Earth unless the citizens surrender. Meanwhile, the Turtles are in Paris with Splinter, who is showing them the sights via the sewer system. Shredder, Bebop and Rocksteady arrive in Paris with the device, which they charge with Paris' electrical power system. April arrives to cover the story of mysterious power failures in the City of Lights, and gets captured by Shredder. The Turtles head for the rescue as Rocksteady and Bebop blast everything in sight with their rust encruster. They stop the rusting as the Eiffel Tower itself begins to collapse from rust. The Turtles rescue April and just in time, Donatello reverses the rust encruster and saves the Eiffel Tower.

In the Austrian Alps, Krang plans to use his new invention to melt the Alpine glaciers, flooding the low-lying villages.

The Turtles take a tour of Venice, Italy, just in time for the annual Mardi Gras festival, which April O'Neil is covering for Channel 6. Meanwhile, Shredder & Krang plan to hold the priceless treasures of Venice to ransom by using Krang's HydroFluxor to flood the city.

Two intergalactic art collectors are stealing the priceless artworks from the museums of Florence, Italy. The aliens are taking only artworks designed by the Renaissance masters that the Turtles are named after.

The Turtles & Splinter arrive in Lisbon, Portugal, just in time for the annual Running of the Bulls. Meanwhile, Shredder & the mutants will use Krang's new heat ray magnifier to burn the city to ashes using the power of the Sun unless the Turtles can stop them.

The TMNT & Splinter journey to Dublin, capital of the Republic of Ireland, land of myth & legend. Meanwhile, Shredder, Rocksteady & Bebop use Krang's Rainbow TransCharmer to transform all of the cute, furry animals in Dublin into vicious beasts.

Shredder takes possession of the mythic sword, Excalibur, and proclaims himself "King Shredder". The Turtles, along with Merlin, must take it from him or else the Medieval period will merge with the modern world.

The Turtles & Master Splinter travel to Athens, Greece, while April & Irma buy a mysterious amulet from a flea market vendor. Unfortunately, Krang & Shredder have tracked enormous power readings straight to April's necklace, which is slowly transforming her into the Queen of the mythical underwater city of Atlantis.

The Turtles take a trip on the famous Orient Express that runs from Gare de Lyon in Paris, France to Istanbul, Turkey. But Shredder is also on board and is planning to use Krang's new Super Charger to launch the Orient Express into the world's largest oil field.

The Turtles and April are in Amsterdam. April is covering the showing of the world-famed Duchess Diamond. Krang wants the diamond, a flawless stone, to focus the rays on his Laser Dimension Blade, which will cut through the dimensions and bring the Technodrome to Earth. Krang sends Shredder and the mutants to retrieve it, but they're foiled by a low-rent diamond thief, Spats Sparkle. There's a smelly battle at a cheese warehouse and a climactic chase at an abandoned windmill.

A descendant of the Viking raiders, Eric Red, seizes both April and Professor Swenson's map to the underground volcanos in Scandinavia. He plans to tap into the molten energy, melt the polar ice cap and flood the world's coastal cities, making them easy prey for his wanna-be Vikings. The Turtles battle Eric's ""Hammer of Thor,"" fight a mechanical sea serpent and stop the guy before he blows up the volcanoes.

After experiencing a time-slip with an atomic clock, the Turtles find themselves in 1890, where they meet the famous detective Sherlock Holmes & his assistant, Dr. Watson, hot on the trail of Professor Moriarty, who has stolen the atomic clock with intentions to rule the future. The Turtles must retrieve the atomic clock before Moriarty uses it to change history & proclaim himself Emperor of the World.

After a fight with Shredder causes Donatello to be struck by a laser beam, his personality changes to become a costumed superhero known as the Dark Turtle. His mission: Seek out & destroy Shredder. Meanwhile, a dinosaur-like alien race called Triceratons, invades Earth.

A small alien being, named Quirx, crash-lands on Earth, with intergalactic stormtroopers in hot pursuit. The Turtles must figure out how to get Quirx back to his home planet, before Earth is destroyed.

Shredder uses a time machine to travel back to Ancient Japan in the year 1583. He plans to defeat Hamato Koji, the man who founded the Foot Clan, and Splinter's great ancestor, for if Hamato Koji is defeated, then Master Splinter would never have been born and the Turtles would forever remain ordinary turtles.

Two convicts from Dimension X are brought to Earth when Donatello's Portable Portal Generator malfunctions. Unfortunately, Vernon & Irma are transported to the Dimension X Penitentiary in their place. The Turtles must defeat these convicts & somehow save Irma & Vernon.

While Splinter's sensei, Mogo-san, is visiting New York, a criminal gang of ninja, known as the Black Heart Gang, are terrorizing the city with a crime spree, and Mogo-san's grandson, Yoku, is their leader. The Turtles & Splinter must stop Shredder & the Black Heart Gang from stealing secret maps of nuclear missile sites.

In an attempt to finally defeat the Turtles once and for all, Shredder assembles Leatherhead, Tempestra, Scumbug, Chrome Dome, Antrax, The Rat King and Slash to form a team that proves too much for the Turtles to handle on their own.

The Neutrinos return and assist the TMNT in keeping a new invention out of Krang's clutches.

Kerma the space turtle returns once again for the Turtles help in programming his city's new defence robots but Groundchuck and Dirtbag have also returned to the city to cause trouble.

Baxter Stockman & his alien computer return to Earth from the Dimensional Limbo & take possession of Shredder's Retro-Mutagen Ray Gun. After stealing the essences of various insects & arachnids, he uses them to turn people into mutant insects & arachnids. The Turtles must battle the creatures & turn the people back to normal.

The Turtles discover an Atlantean city, not in ancient Greece, but in modern times. After meeting Merdude, in reality is the true King of Atlantis, the Turtles must defeat Shredder & dethrone Bebop, who been set up as a puppet king.

Professional mutant hunter Dirk Savage is conned into to rounding up New York's mutants. Tokka, Rahzer, two of the Punk Frogs, Leonardo, Michelangelo, and Mondo Gecko all fall prey and become part of a mutant slug's army.

Krang makes copies of himself and sets them loose to attack the turtles.

A new amusement theme park has opened with Shogun, Medieval & Future themed attractions. The Turtles are invited to try out the attractions, but when the robots in the park start to play too rough, the Turtles are in big trouble.

After bringing the Technodrome back to the surface, Shredder and Krang trap the Turtles and send them to Dimension X where they become slaves. In the meantime, Shredder and Krang are back on Earth once again as they try to take over the world.