In the dank world beneath our feet a sewer worker fuses with a huge slime mold and threatens to slime the world above - the world of humans. Ty and Abby race to find a way to stop the slime creature before it engulfs the city.
The Scab Fairy (the Tooth Fairy's grosser cousin) is taking scabs without even leaving a quarter under kid's pillows! Has the Scab Fairy gone bad or is this evil villainess some sort of twisted imposter? Abby and Ty try to stop her before she carries out her revenge - and disappoints a whole lot of scabby kids.
A crime wave has hit the city and the cops can't stop it - they're all down with a case of diarrhea! Coincidence? Bad Potato salad at the police picnic? Nope, it's the work of Lance Boil, ex-Grossologist turned super villain. He's developed a weapon that'll send your bottom right to the toilet. Can Abby and Ty stop him before everyone is hopping on one foot or will the whole city go down the toilet?
An outbreak of head lice and a lock down in quarantine is too much for our Grossologists - Ty and Abby break up as a crime fighting team. But it turns out that these lice aren't the run-of-the-mill variety - Insectiva is back and this time she's out to enslave kids with mind-controlling bloodsuckers! When Abby becomes one of Insectiva's zombie drones Ty must rescue her. But can he do it without his partner?
A team of mysterious, slimy thugs had been terrorizing the waterfront and eating all the fish. With a new kitten to feed and the cat food supply threatened, Ty and Abby set out to locate the thieves and restore the fish supply - only to discover that the culprits are giant, mutated Hagfish - the grossest fish in the sea!
When the GRS-1 comes up short, Ty and Lab Rat design and build the TYMOBILE - a kicking set of wheels that can crawl, leap, or otherwise get around just like your favorite insect. But when Ty's goaded into a race by Insectiva and her cadre of giant bugs, it's all part of her evil plan to plant ultrasonic generators in the country, allowing her to control a cloud of locusts and cover the city with the hungry insects!
There is a new kid in school, who kind of smells. This repels most kids but attracts Ty and Abby. It turns out that through a science experiment mishap he now has the 'rotting touch' and everything organic he touches rots immediately. Can Abby and Ty cure him...or does he really want to be cured? Watch as a new, rotten villain is born!
When Ty personally stops the latest of Lance Boil's evil plans, the ex-grossologist villain decides to deal with Ty once and for all. After miniaturizing himself and tricking Ty into drinking him, Lance races through Ty's veins headed for his cerebral cortex. His plan - turn Ty into a drooling vegetable! Luckily, Abby's not afraid to dive in after Lance - too bad Ty refuses to sit still and let her work, he's got a school battlebot competition to win!
Instectiva, Lance Boil and Sloppy Joe join forces to take down the Bureau of Grossology by afflicting the members simultaneously with villain sized doses of internal parasites, halitosis and acne. Can the now incredibly gross looking, smelling and feeling Grossology team overcome these afflictions before the Gruesome Threesome take over the city?
When Abby defuses a mysterious device Lance Boil planted in the middle of town, she gets bathed in a green ray that instantly starts her aging at 6000 times the normal rate! Now, she and Ty have to track down Lance, reverse the process, and stop him from unleashing the ray on the entire city - turning everyone into octogenarians! Worse, they have to do it before Abby ages her way into diapers again!
It's science competition time at Ringworm jr. High, only this time there's a new challenger for Ty's crown - Patrick, a kid with as much science knowledge as Ty himself. But when Ty decides to up his fruit-fly evolution project with a little mutagenic kickstart, things go wrong almost immediately. Now, he and Abby are up against terrorizing fruit flies that can breed and evolve so quickly that it seems like nothing can stop them. Unless Ty's willing to ask Patrick for a little help...
Ty and Abby get stuck in the school with Paige and Naomi when they miss a bus that is to take them camping with their class. If this were not troubling enough, they find that a mad proctologist, Dr. Colon, is using the school as a breeding ground for a giant intestine that he intends to snake around the world. But what is his ultimate plan?
When people start showing up with bite marks on their necks, Ty and Abby can't help but wonder if maybe vampires aren't a myth after all. But when they dig a little deeper, they discover that it's another kind of blood sucker that's causing trouble - leeches! Worse, these hungry invertebrates are led by 869, a giant mutated talking leech that's had enough of his kind being trapped in hospitals under harsh florescent lights. He only has one goal: freedom for leechkind!
Gassy super villain, Fartor returns with a scheme to fart-up the entire planet! But with a plan this big he needs help - and he's got his sights set on Ty. What will happen to our team of grossologists when one of them turns to the fart side?
A new nocturnal villain, Darko Crevasse, plunges the city into darkness with the help of his army of creatures of the night. Ty and Lab Rat scramble to shed some light on the problem before it's lights out for everyone.
Abby and Ty are jazzed to be contestants on the hottest game show on the planet where their gross skills and iron stomachs could make them stars. Only trouble is, the show is an elaborate trap and Lance Boil is behind it all! With Abby and Ty out of the way who will stop Lance's pus plan?