Robot heroes in training Elmo, Cookie Monster, and Abby Cadabby use their STEM superpowers to solve wacky larger-than-life problems.
A giant pie is sent to Pretty Big City to stop an asteroid… but the Mechas and friends have eaten the whole thing!
The Singing Stone Heads are ready to perform at the Museum, but when they open their mouths, they sneeze instead of sing!
Ranger Nat is stuck at the bottom of the crevice, but the problem grows when Mecha Abby also gets stuck.
Zee is ready to launch his rocket into space, but when the launchpad breaks, the rocket is launched into the farm instead.
When Big Old Boulder rolls down the hill towards the museum, Berta needs the Mechas help to keep it stable.
It's Food Day in Pretty Big City, but the Mechas need to help when the banana atop the banana split statue is not split!
The magnet crane at the construction site accidentally turns on, sucking up all the metal, including the Mecha Builders!
Roof is delivering eggs to Marwyn at the Train Station, that is, until the train pulls into the station and can't stop!
Hero Celebration Day is finishing with a slideshow of everyday heroes, that is, until the projector screen rips.
Pretty Big City is cooling off with an ice slide in the park, but the situation gets slippery when the slide starts melting.
Farmer MacBarm is hosting the Sunny Field Farm Chicken Roll, but the race gets off to a slow start when the chickens don't roll.
Ranger Nat can't wait to see Pinecone's Comet, that is, until his telescope falls to the bottom of a cliff.
It's the Pretty Big All City Read and Izzy and Barb are ready, that is, until all the books go missing!
Pretty Big City finds itself in a sticky situation when the factory starts spewing super sticky slime everywhere!
Ranger Nat's hike turns to adventure when he finds a treasure map. The only problem is that he can't read it.
Zee and MacBarm are setting up their corn maze with the help of Zee's Zee Mobile... that is, until it breaks down inside the maze.
The windmill isn't turning, which means Sunny Field Farm has no power. The windmill needs to turn again so Zee can launch his rocket!
Izzy and Timmy are making a bird caller for Grandma, but have trouble connecting pieces of their machine.
MacBarm is bringing food to his hungry chickens, that is, until all of the food falls out of his truck.
Grandma and her twin sister want to recreate their old zipline act, but quickly discover that the zipline no longer exists!
Berta is opening an exhibit on the Whatsacallit of Treetop Woods. If only she could get a picture to prove it's real.
Gerry and Nat are leading the Treetop Troops on a hike, but Nat finds himself lost in the woods as it gets darker.
It's MacBarm's croquet tournament and Zee made giant decorations but they're too big to get to the farm.
It's the opening day of the skyscraper and the Mechas need to put the sphere on top of the building before the ribbon cutting ceremony.
Zee's growth ray turns Moobert giant, but when a storm rolls in, the Mechas need to build a shelter big enough to fit her.
After Ranger Nat's kite blows away in the wind, the Mechas and Timmy learn to build their own kite to find it.
The train needs to cross the ravine, which becomes difficult when the Martians accidentally break the bridge.
The Zee Mobile is great at counting the chickens at the farm, but won't stop crashing into and ruining MacBarm's barn door.
Grandma and Timmy are entering the Pinecone Art Show by carving a sculpture out of stone… that is, if they can learn how to carve.
Ranger Nat is hiking and comes across the Big-Footed Cave Bird, and realizes it can't get back into her home.
When the ornaments on the Pretty Big City tree break, the Mechas must build new ones and save the holidays for their friends.
It's time for Zee and MacBarm's gift exchange, but the snowman scarecrow Zee made for MacBarm keeps blowing away!
Lloyd's testing a wind-up powered go-cart, but a problem arises when it keeps running out of energy.
Sif's coming in for a landing at the rocket launch site - until her rocket is pushed off course by a satellite!
Lloyd is selling silly hats at the factory, but when the hat machine malfunctions it starts raining silly hats on Pretty Big City!
Zee makes a giant rocket ship in a bottle, but things take a turn when he gets stuck inside!
It's MacBarm's day off and Zee takes over harvesting carrots with his Zee mobile, but when it breaks, the work still needs to be done.
Ranger Nat is bringing a playhouse on the train for Timmy and Izzy, but it won't fit through the tunnel!
The Martians come to Pretty Big City but find themselves in need of help when they are unable to land their spaceship.
Zee needs to communicate with Sif in outer space but can't because a bird has made its home on top of the satellite dish!
Panic erupts in Pretty Big City when the big clock breaks and no one is able to tell what time it is.
Zee is showing off his inventions at his rocket-powered show, including his latest creation, a rocket powered Ferris wheel.
It's Halloween and everything is set for the Zee Mobile to pull the haunted hayride… until it drives away.
Timmy can't wait to trick or treat as a Mecha T-Rex, but his Halloween is almost ruined when he can't reach the arms to his costume.
Zee's new drone accidentally doubles as a cow caller, and the cows keep leaving the farm to go see it. But how?
Marwyn attempts to make Pretty Big City's largest cookie, but to do so, he'll need a lot of help.
The Martians want to help Lloyd deliver packages, but keep breaking them when they drop them from up high.
MacBarm and Zee built a slide that sends people all the way across the farm… which means people spend more time walking than sliding.
Izzy and Timmy go to dig up treasure at the top of Lawrence Pinecone's Statue's shadow… only to find that nothing's there!
The mysterious "Pretty Big Thing" is scaring the people of Pretty Big City from going to work… but what is it?
