Mia shows Oskar her hand-drawn comic book when a new girl, Tilly joins in. Mia takes them to the fantastic world in her book where they explore and find new friends Rainbow Guy, Beetroot Girl, the Leafthings and Nice Cream Bear. Together they find they all have something to offer in friendship.
When Mia, Oskar and Tilly cannot find anywhere to play they decide to go and build their very own playhouse. Ice Cream Bear and the Leafthings help with Rainbow Guy bringing the colour, of course. Mia, Oskar and Tilly discover that making the playhouse with their friends was the most fun part.
Tilly gets very excited about playing superheroes. Mia, Oskar and Tilly all go to see what a superhero like Beetroot Girl is doing. They each explore ways of using their own superpowers to help save Watermelon Cat who is cat stuck up a tree. In doing so they discover its not necessarily the obvious things that make you super.
Tilly won't stop soaking Mia and Oskar by splashing in puddles. Soon they are all underwater where they meet Octobubbly. He is in fits of laughter blowing bubbles everywhere. To Mia, Oskar and Tilly's frustration Octobubbly won't stop his game even when he is asked because he is having so much fun. They learn you have to respect other people's views.
Oskar is bored and it seems nothing Mia and Tilly suggest can cheer him up. Eventually Mia and Tilly persuade Oskar to go with them to a fairground but it is only when they meet Nice Cream Bear does Oskar see that his bad mood has been ruining Mia and Tilly's fun. All changes when they all try out the rollercoaster!
Mia, Oskar and Tilly are on a treasure hunt when Tilly mysteriously disappears, has she taken the treasure chest of sweets? With the help of Nice Cream Bear Mia and Oskar find Tilly, the treasure and Mrs Drago the friendly dragon deep in the forest. Not everything was what they had thought.
Mia is on the swings with Tilly and Oskar when her wobbly tooth suddenly falls out. Mia discovers a timid Gumbelina has ended up with the tooth, but she keeps running away! The bouncy furry Teeth Furries are after the tooth and the children need to get it back from Gumbelina before they do!
The children want to join a football game but the big boys say no because they're too small. So undaunted they go to the forest to play with the little Football Nuts but the big SoccerSauruses storm in and ruin it. Only Mia, Oskar and Tilly's size can save the game because sometimes being smaller is helpful!
Tilly is excited about her new pet dragonfly but just when they all go in search of a friend for her pet the dragonfly escapes and the tables are turned as a giant bee called Bee Bop has his own ideas of who he would like as pets! Tilly has to save her friends along with her dragonfly. They all learn what it means to fly free.
Mia, Oskar and Tilly decide to play house and find some newly hatched chicks to look after. It's Tilly's turn to play Mummy but she doesn't want Mia and Oskar's help. Before long though, its chaos and the chicks are running everywhere. Tilly realises that it's all much more fun when everyone's helping out.
When there just isn't enough time for playing, Mia, Tilly and Oskar enlist the help of Buckley—a genie in a bucket. Buckley grants them three wishes and they choose to stop the clock so that time is endless. However, the children discover unexpected hurdles with time stopped, but they've used all their three wishes… How will they start up time again?
Tilly is so excited about playing Whirley Ball but there are no rules, until the children start to make them up. Nice Cream Bear plays too, and even Octobubbly joins in with his tentacles producing a real tangle. Mia, Oskar and Tilly have such fun making the game up that it doesn't matter who wins in the end.
Oskar is showing off his knowledge about space in the playground. The children adventure off to the moon to find out more with moon. With Rainbow Guy and Rocko Panda they learn about gravity and Oskar realises if he uses his imagination there can be fun as well facts.
Mia is a fast runner and Tilly challenges them all to a race but thinks Tilly is pretending to lose. A competitive Rainbow Guy finds them in the forest and asks to race. This time Mia shows how fast she can run, and when the result is revealed, she learns how to be happy for someone else.
Mia, Tilly and Oskar meet Max, a new kid in the playground, but Oskar isn't very kind. When they go off to space for an exciting adventure across the Milky Way, Oskar shows off. When they meet Smarty the Lighthouse, Mia makes sure Oskar learns he doesn't know everything, and so Oskar comes to realize how he has been treating Max.
Mia is upset when she discovers her favorite climbing frame has been taken down. In the forest she finds NCB wants his old shoes back but they keep running away. The children help him to see he's much too big for his old shoes, and Mia discovers that sometimes you have to let go of things in the past as you grow.
Mia and Tilly are excited about pretending to be puppy dogs, but Oskar wants to build a sandcastle instead. So Mia and Tilly run into the forest barking like puppies and bump into Smarty the Lighthouse who has lost her lightbulb. Together with Oskar they find the lightbulb deep underground.
Mia is torn between Oskar and Tilly, who want her to play different things at the same time. Mia tries to please them both by running between skipping in the forest with Tilly and space with Oskar. Eventually she becomes frustrated, and Tilly and Oskar realize they should all have a say in what they play.
The ball with which the children are playing mysteriously bursts. What could have done it? Off to space they go to find out what it could have been, but Oskar is acting a little strange. He has a confession to make, and when he does, he discovers owning up is great and brings him closer to his friends.
Mia and Tilde want to play, but Oskar cannot imagine the strange things they suggest, so they go to a new world without him. It's a topsy turvy world of opposites, and they have lots of fun discovering what happens there. Oskar, who loves logic and facts, is finding it difficult to imagine it is real, so the girls help their friend to believe and enjoy Opposite World.
Tilly wants to play with her radio-controlled car, but the others don't have cars. Instead, Mia and Oskar have fun with some friendly racing snails they find. Suddenly Tilly challenges them to a race in her Monster Truck. Can Mia and Oskar's racing snails beat Tilly's super fast truck?
The kids are excited by Oskar's digital tablet. On the moon Oskar only wants to watch his Robo Carrot tablet, but Mia wants to play. When Beetroot Girl leaves Mia in charge of her Asteroid bunnies, havoc starts, and they find it can be more fun to be active rather than sit back and watch.
Oskar and Tilly are playing with a frisbee when it knocks Mia into a garbage can. Mia starts to collect the litter, but without any help from Oskar or Tilly. Mia finds that collecting the trash can be like a video game, and she has fun collecting gold with the help of Nice Cream Bear's tummy. Oskar and Tilly join in and help clear up too.
Mia, Tilly and Oskar want to put on a song and dance show, but deciding what to do is tricky. Mia takes the lead but then hurts her leg, leaving Tilly and Oskar to rehearse. Whenever they wonder which is the right way to turn, they think about what Mia would do. Mia returns just in time for the finale, and all their friends join in too.
