The Martians are headed to Pretty Big City but find themselves in need of help when they are unable to land their spaceship. The Mechas use inspiration from their surroundings to build a safe space for the Martians to land./Zee needs to communicate with Sif in Space but can't because a bird has made a nest on top of his satellite dish! The Mechas need to make a new nest away from the satellite that makes the bird happy and allows Zee to talk to Sif.

Lloyd's truck is broken, so the Martians volunteer to help deliver packages. After the Martians break several of the packages, the Mechas step in to keep everyone's deliveries safe./MacBarm and Zee's Super Duper Sled Slide goes really fast and really far, which means more time is spent walking then sliding. The Mechas need to figure out a way to stop everyone from sliding out too far.

Panic erupts in Pretty Big City when the big clock breaks and no one is able to tell what time it is. The Mechas need to replace a broken gear in the clock in order to keep the hands moving and set the city to the right time./Zee is showing off his inventions at his rocket powered Ferris wheel at his invention show. When it loses control and falls down the Mechas need to find a way to lift it on its side so they can roll it back for Zee's presentation.

A treasure hunt turns to mystery when Izzy and Timmy go to dig up treasure at the top of Lawrence Pinecone's Statue's shadow and find nothing there! The Mechas need to help Berta find the pinecone to save the treasure hunt./The mysterious "Pretty Big Thing" is scaring people from going to work, so it's up to the Mechas to find out what it is. However, the situation takes a turn when they discover that the Pretty Big Thing is actually only its shadow.

Berta is taking a picture with Big Old Boulder for the museum, but needs the Mechas help when the boulder rolls down the hill towards the museum! The Mechas need to work together to get the rock back up the hill, and keep it stable. / It is Food Day in Pretty Big City, but when they unveil this year's celebratory statue, they realize the banana atop their banana split statue is not split! The Mechas need to split the banana statue quickly, before all the Food Day ice cream melts!

The Martians come into Pretty Big City and accidentally break all the ornaments on the Pretty Big City tree. Since the holidays can't start without a decorated tree, the Mechas need to create new ornaments and fast./It's time for Zee and MacBarm's gift exchange, but the snowman scarecrow Zee made for MacBarm keeps blowing away! The Mechas need to help Zee build a scarecrow out of a new material - one that won't blow away from a rocket launch.

The magnet crane at the construction site accidentally turns on, sucking up all the metal, including some of the Mecha Builders! The Mechas need to figure out how to stop the pull of the magnet before more of people's belongings get sucked up. / Roof is delivering eggs to Marwyn at the Treetop Woods Train Station. When he tries to stop, the brake lever snaps, leaving the train unable to stop. The Mechas need to save the train without dropping any of Marwyn's eggs!

There's a leak at the space station and the solution is Zee's super sticky slime, until it spills on Zee and MacBarm, who get stuck together. It's up to the Mechas to get them unstuck so they can do their super-epic space rescue./The Martians send a giant hunk of ice to help cool off Pretty Big City on a hot day, but the ice is heading straight for the skyscraper! It's up to the Mechas to find a way to stop the ice from destroying the city.

Hero Celebration Day is finishing off with a slideshow of the everyday heroes of Pretty Big City, but the Mechas need to save the event when screen rips. The Mechas need to find something flat and opaque to properly show off the photos. / Pretty Big City is cooling off on a hot day with an ice slide in the park, but the situation gets slippery when the ice slide starts melting. The Mechas have to figure out how to stop the slide from melting, so their friends can have a fun day.

A giant pie is sent to Pretty Big City to stop an asteroid... but that discovery is made only after the Mechas and friends have eaten the whole thing. Now it's up to the Mechas to find a replacement substance to catch the asteroid. / The Singing Stone Heads are ready to perform at Big Old Boulder Museum, but when they open their mouths, the only sounds that come out are sneezes! The Mechas have to figure out what's causing the sneezing and how to stop it to save the concert.

Farmer MacBarm is hosting the first annual Sunny Field Farm Chicken Roll, but the race gets off to a slow start when the chickens don't roll. The Mechas realize that gravity will start the race and build ramps to get the chickens moving. / Ranger Nat needs to get his telescope to the ranger tower to see Pinecone's Comet, but things go downhill when the telescope falls to the bottom of the cliff. The Mechas arrive to save the telescope, but get themselves and Ranger Nat stuck as well!

Ranger Nat is stuck at the bottom of the crevice with no way to get up, but the problem grows bigger when Mecha Abby gets stuck trying to save him. The Mechas need to find a way to free Abby from the tree so they can lift Nat out. / Zee is ready to launch his rocket into space, but when it takes off, the launchpad breaks and the rocket is launched into the farm instead. The Mechas have to get the rocket back to Zee's launchpad and point it back upwards.

It's the Pretty Big All City Read and Izzy and Barb are all set up, that is, until all the books end up missing on account of the yip yips. Now, the Mechas need to locate the books and get them all back to the library before the event starts. / Pretty Big City finds itself in a sticky situation when the factory starts spewing super sticky slime everywhere! The Mechas need to clean up the city and help Marwyn rescue his food truck from a giant pile of slime on the road.

MacBarm is bringing his chickens a new trough full of feed, that is until it falls out of his truck and breaks. The Mechas need to help him find a new container for the chicken feed, and fast, as the chickens are getting hungry. / Grandma and her twin sister return to Treetop Woods to recreate their old zipline act, but quickly discover that the zipline no longer exists! The Mechas must measure and build a new zipline so the Zipline Sisters can ride again.

Ranger Nat's hike in the woods turns to adventure when he finds a treasure map. The only problem is that he can't read it. The Mechas resolve to help him read the map and follow the directions that lead them to buried treasure. / Zee and MacBarm are setting up their corn maze with the Zee Mobile... that is, until it breaks inside the maze. The Mechas need to find Zee and learn that by creating a map they can navigate the maze, find him and open the maze.

Berta is opening an exhibit on the Whatsacallit of Treetop Woods. If only she could get a picture to prove to everyone it's real. She and the Mechas set out to take its picture without being spotted, and find out its identity. / Gerry and Ranger Nat are leading the Treetop Troops on a hike, but soon discover Nat is lost! The Mechas need to find Nat before it gets too dark, until they realize that they can use flashlights to not only see, but communicate.

The windmill is broken, which means there's no power at Sunny Field Farms. After figuring out that the problem is a broken blade, the Mechas try different materials to fix the windmill and restore power back to Zee and MacBarm. / Izzy and Timmy are making a bird caller for Grandma, but have trouble connecting pieces of their machine. The Mechas search for items that will move the machine along and help the kids call birds for grandma.

It's MacBarm's croquet tournament and Zee made giant decorations. The only problem is that they're too giant to get to the farm./It's the opening day of the skyscraper and the Mechas need to find a way to put the sphere on top of the building before the ribbon cutting ceremony.