A robotic music machine from Aunt Jenny's early days as an inventor goes haywire. Riley, Alex and Theo transform into Megablast to save the day in an adventure in which Theo/Thunder must overcome his unease about improvising. Not only do they save the town, they also write a new song in the process!
Megablast is preparing for a show at the local retirement home. However, the band starts to have creative differences when Alex wants to rock hard while Theo wants to make a sound that's more chill. Their practice gets derailed quickly when they learn that Kaboom has unleashed his new device on Greenville: a machine that's turning everyone into babies! Together, they work to thwart Kaboom's plan while also coming up with a stellar mashed-up new tune!
When an ice cream truck's jingle breaks down, Megablast is happy to help by playing the sickest jingle of all time. The band draws so many customers that the truck sells out of ice cream - meaning the town brat and villain Stewey doesn't get any. He throws a tantrum and becomes Gooey who uses ice-slime to turn everyone into freeze-brained minions to rip the town apart in search of ice cream for him. Megablast transforms into Rocket, Thunder and Metallix to save the town and restore everyone to their regular selves.
Riley is struggling with her newest song. She keeps trying to improve it with layers and effects, but instead of making it better, it just sounds muddy. Meanwhile, Starlet's vocal tuning software goes haywire and creates a super powered mega magnet that attracts all the metal in town! To stop her, Megablast transforms into Rocket, Thunder and Metallix and need to convince Starlet that she doesn't need the digital enhancements and that her voice is perfect just the way it is.
Riley is challenged to get the band acting as a cohesive team when Alex develops a love of loooong drum solos. Meanwhile Kaboom is bringing all of Greenville under his control with his latest invention - hypnotizing glasses called "Idolizers" that make people see him as a genius. Megablast transforms into Rocket, Thunder and Metallix to save the town and Metallix makes the mistake of thinking he can handle Kaboom solo which backfires big time and leads to Rocket, Thunder and Trix falling under Kaboom's control. Metallix sees just how important being a cohesive team is and Rocket comes up with the perfect solution save the day.
Megablast writes an awesome new dance song called "The Megablast Dance". Beatrix uploads a video of her dancing to it. Soon everyone in town is seeing it online and dancing to the video which Starlet is horrified to discover is now more popular than her on the internet. Starlet will do everything in her power to end Megablast's popularity surge, even if it means destroying the internet!
Megablast goes up against Metal Mike and the Drones to make videos for a contest that will be shown at the drive-in. Megablast's video is directed by Riley's mom while the extreme pyro and special FX of Metal Mike's video threaten to destroy Greenville. The kids find themselves with the difficult challenge of having to be in two places at the same time - shooting a video as Megablast with Riley's parents and saving the town as super heroes - all while trying to ensure that their secret identities aren't blown!
Local horticulture enthusiast, Dr. Dandelion, engineers a Stink Monster odorous enough to force all the residents out of town! Even worse, the smell causes Alex to lose his grove. Our Superheroes must find a way to defeat the ever-growing Stink Monster before it turns Greenville into Stinkville! Together, Megablast has to find a way to drive the stink out of town while learning that believing in each other is the best way to save the day.
Riley, Theo and Alex are at a monster movie when they discover scoring - the music played over movies to make it feel a certain way. Megablast decides to take it to the streets and provide live scoring for people. They can make any activity fun, dramatic or even scary! But it turns out they weren't the only ones who learned something from the movie. The Rachels, AKA the Copycats, have taken the form of the movie monsters in order to scare everyone out of Greenville and turn it into their own skatepark. Megablast transforms into Rocket, Thunder and Metallix to settle the score
Riley is so focused on the writing of a new song for Megablast that she doesn't have time to play with Beatrix. Beatrix feels invisible and runs away. She's in for a big surprise when she accidentally eats some of Dr. Dandelion's Gigantor Cabbage and grows to the size of a building and is tricked into being in Dr. D's posse. Megablast transforms into Rocket, Thunder and Metallix to get Beatrix shrunk back to normal size and home safe before she accidentally stomps Greenville into rubble. Riley realizes that she should have paid more attention to her friend and uses the one thing that Beatrix can't resist to show her how much she cares: music!
It's the day of Beach Bash, a big beach concert in Greenville. Megablast is the opening act, but Riley can't help but feel a little disappointed they don't get to play a full set, like headliner Zozo. Meanwhile, Stewey wants a snow globe, but when his mom tells him to wait for his birthday, he goes into a super snit, transforms into Gooey and traps all of Greenville under a snow dome of his own making! Megablast transforms into Rocket, Thunder and Metallix to get the dome down in time for Beach Bash.
It's Green Fest and Greenville's power is going green thanks to a new wind turbine. Megablast has been asked to play at its grand opening event where they'll be performing a new song about caring for our planet. But when Riley gets interviewed by a videographer, she suddenly gets tongue-tied. It looks like she might not be able to perform! Then Metal Mike crashes the party and really threatens to derail things by taking over the stage with his sound-polluting, air-polluting music. Megablast transforms into Rocket, Thunder and Metallix to save the day, and Theo and Alex help Riley get over being tongue-tied.
Megablast is excited to be participating in the Greenville Talent Show and are working on a song for it. But the Copycats want to be the winners and lock Megablast up to keep them from performing. Then, when the Copycats realize they don't know who else is performing, they lock all of the citizens in town in their homes just to be sure they won't have any competition. Beatrix and Aunt Jenny help Megablast bust out. Megablast transforms into Rocket, Thunder and Metallix and must free the trapped townies and thwart the shape-shifting trio before their talent for mayhem takes over!
Megablast is excited to play the school dance. Meanwhile, Stewey is listening to his favourite song on a tablet device, but it abruptly stops when the battery dies! This doesn't go over well with Stewey who becomes Gooey and he slimes anything that plays music because he doesn't want to hear any music if it can't be his favorite song. Megablast transforms into Rocket, Thunder and Metallix to save the day and get back to the school in time for the dance start.
Riley finds an old song that her Mom wrote long ago and Megablast decides to sample it in their latest song. Meanwhile, Dr. Dandelion has created a giant Jack and the Beanstalk-esque plant penthouse over Greenville. When the beanstalk's vines start swiping things to furnish the new pad, Megablast must transform into Rocket, Thunder and Metallix to stop the pilfering plant before the weight of all the stuff it's swiped makes it collapse on the town.
Riley and Theo both have chores to do today, meaning they won't be able to get together with Alex to jam. Alex is super disappointed, so when he discovers that Kaboom has invented robots to do people's work for them he eagerly gets each of his buddies one to do their chores. Even though their instincts tell them it's a bad idea to get mixed up with one of Kaboom's inventions Riley and Theo can't resist when they see that the robots actually seem pretty good.
Aunt Jenny is set to compete in the annual Greenville gokart race. With help from Riley, Theo, Alex and Beatrix they put together the Megablaster, an elite go-kart with a great chance at winning. When Kaboom hears about the prize and glory that comes with winning the race, he decides to build his own go-kart - by taking vehicle parts and items from all over town. Megablast transforms into Rocket, Thunder and Metallix to do damage control.
Riley and the guys are helping Aunt Jenny pack the van. She's on her way to a family hoedown in the country. Riley will miss her but is happy Aunt Jenny gets to go and enjoy home. But not so fast. Dr. Dandelion creates seeds that turns the streets of Greenville into swampland, planning to get its citizens to be unimpressed and leave Greenville for good. Aunt Jenny wishes she could leave for the hoedown but her van gets stuck in the swamp.
Riley starts the day off trying to beat her time for putting her shoes on and falls short. That's ok, she'll keep trying. Meanwhile, Kaboom uses his new sleeperizer invention to put the people of Greenville to sleep. That way he can work on his inventions in peace and quiet! Megablast is spared because they have headphones on while making a recording, but Aunt Jenny falls asleep along with the rest of the town. Megablast transforms into Rocket, Thunder and Metallics to save the town.
Riley is excited to help Jon write a song for a gig - his first gig in years. But the approaches that Riley and her Dad have to song-writing are very different, and cause tension. Meanwhile, Metal Mike gets a bad review and decides to up his performance game, with ridiculous demands that make the drones cause trouble in town. Things escalate when Metal Mike crashes the party and Rocket goes head to head to save the party gig for her dad and at the same time.
When Riley films a Day in the Life Of... segment for the local news, a jealous Metal Mike takes over the airways with a viral video to steal all the fans in Greenville for himself. Megablast transforms into Rocket, Thunder and Metallix to take back the airwaves and teach Metal Mike that making friends and winning fans isn't something you can force on people.
Riley is having a bad day. All kinds of little things have gone wrong and she's feeling down. Theo and Alex try to cheer her up by getting on with what Megablast does best - write music! But even that hits snags. It all leaves Megablast wondering, are bad days contagious? Meanwhile Kaboom has a new invention that can make anyone spill the beans. His diabolical plan: to use it on Rocket.
The newspaper is looking for a local Changemaker and Theo thinks Riley would be the perfect candidate; Rachel one learns of this and wants the front page all to herself, so she begins to drown the town with loud music, causing noise-related mayhem.
Megablast decides to try writing a disco song. Meanwhile, Starlet hatches a brilliant plan to give away free merch to help her make the comeback, but accidentally forces the town to perform her signature dance moves, whether they like it or not!
It's an exciting day for Megablast; they're about to drop their first EP; but tensions start to develop when the band can't agree on anything; after they find themselves stuck in AJ's lair, things escalate quickly, and they decide to break up.
Tensions in the band are at an all-time high, as a trapped Megablast has decided to break up; through some laughter and reflection, they realize they're not just a band but best friends.
Megablast face challenges when trying to make a pump up anthem for the local baseball team, but when Metal Mike goes haywire trying to get a spot on said team, they've now got bigger problems on their hands.
It's Theo's chance to show off his writing and directing skills when his play is chosen for the town's annual show. But when he casts Riley as Little Red Riding Hood and Starlet as the second lead, Starlet causes some turbulent calamities!
Riley and Beatrix enter the pet tricks challenge, but they lose confidence in their act after seeing the other contestants. Meanwhile, Stewey goes full Gooey when he's told he can't have a pet and releases a penguin from the local sanctuary!
When Riley thinks her parents are about to move their family away, she tries to remind them how awesome Greenville is! But it proves to be challenging, as Dr. Dandelion is also out to try and convince everyone else to move away too.