Gilbert has gone missing and Caillou is very concerned. A search of the neighbourhood and the local animal shelter turns up nothing. Caillou thinks about what it would be like to have other kinds of pets, but concludes that Gilbert is the perfect pet and he wants him back! Luckily when they return home Gilbert is waiting for them on the porch.
After a day in the park and a visit to an ice cream parlour with Jeffrey and Jason, Caillou realizes that he has misplaced his new toy car. Mom encourages him to remember where he saw it last. The last place Caillou remembers having it is in the ice cream parlour. When they return Caillou is happy to find that the waitress has his missing car!
Caillou learns all about the jungle at playschool, and decides it would be an exciting place for a game of hide and seek. The other children join in - Leo hides, and the others pretend to be birds, snakes, monkeys and even a lion. Caillou follows the clues until he finally finds Leo, and the brave explorer is happy to see his friend.
When Clementine shows up with a swimming ribbon on her chest, Caillou really wants to have one too. Grandma comes up with some very silly games with ribbons for prizes. Winning isn't that easy, Caillou soon finds out, but he imagines he's an Olympic Athlete and has a lot fun trying his best. He finally does win a ribbon in the straight face contest!
When a new, longer set of monkey bars is installed at the park, Caillou is disappointed that he can't climb as far as Leo. He asks his Daddy how he can get bigger and stronger and finds out that eating right, exercising and getting lots of sleep is the best way. Later, when Clementine and Billy join them Caillou finds he can lift up Billy's bike. He couldn't do that last year! Caillou realizes he's getting stronger every day!
With training wheels on his bike, Caillou is having trouble keeping up with Sarah. After imagining himself riding in a real grownup bike race Caillou decides he's ready to try riding without his training wheels. It proves to be harder than he thought, however, and he quits in frustration. Daddy explains it's okay to wait until he's really ready. He goes back to his training wheels and the next day Sarah shows up on her new roller blades - now she's travelling at his speed.
There's been a big storm and the playschool yard is littered with branches and other debris. The children all pitch in to help clean up the playground . When Caillou and his friends, Leo and Clementine, finish their cleanup duties they decide to build a road through the sandlot. Using simple tools and their imaginations they lay out a road, build a bridge, dig a tunnel, and even plant a tree fashioned from a leafy twig.
When Daddy and Grandpa help a charity build a new home for a needy family, Caillou comes along to help hand out sandwiches. He gets to watch the grownups at work, and imagines himself as a construction worker. He also meets a new friend, Frankie, who shows Caillou where his new bedroom will be.
Mommy and Caillou go to visit an old friend of Mom's and her four-year-old son Kevin. Caillou is surprised to find that Kevin lives in a house in the sky - in an apartment building! He's never been in one before and finds it to be quite an adventure. He likes riding the elevator, and how the view of the city below is just like looking down on the ants in his backyard.
Rosie is teething and just can't seem to fall asleep, so big brother Caillou decides to help. He sings her a song and finds her favourite bunny, but it isn't until he tells her a very imaginative bedtime story that she finally drifts off into the land of dreams.
The Fire chief visits Caillou's playschool to teach the children about fire drills. When Caillou is lifted up for a turn sitting in the big fire truck he imagines he is a firefighter himself hurrying though town to save the day. At the end of his turn Caillou announces he will be a firefighter when he grows up! The Fire Chief says he'd be glad to have Caillou on the team.
After a mischievous Rosie hides Caillou’s cars between the cushions on the sofa, Leo and Caillou have a grand adventure pretending that they are tow truck drivers and crane operators rescuing the cars from their hiding places.
The playschool is going swimming, and it’s Caillou’s very first time on a water slide, but he's a little nervous and doesn’t want to slide down it. Miss Martin tells him it’s natural to be afraid of things the first time you try them - why, she was afraid of the swings when she was a little girl. Caillou musters up his courage and, pretending he’s a brave mountain climber, he climbs up the ladder and slides down, discovering how fun water slides really are!
Mommy and Daddy are going out to a party and Caillou is excited to hear that Grandpa is coming to babysit. When Grandpa arrives he brings a couple of surprises - a book about sailing ships and a real telescope. Caillou learns all about the old ships and how to salute when you say ‘Aye aye Captain!’ When a thunderstorm starts to rage outside Caillou is a little scared, until he pretends he’s a very brave sea captain who’s not afraid of storms!
Rosie doesn’t like bugs - she thinks they’re icky! Caillou on the other hand loves bugs since he learned all about them at playschool. He decides to teach his little sister about all the different kinds of insects in their backyard. Thanks to Caillou’s stories and drawings, Rosie soon likes bugs too, almost as much as Caillou does.
Caillou eagerly awaits the first snowfall of winter, and imagines himself building the biggest snowman in the world. When the snowflakes finally start to fall he rushes outside to play. He and Sarah take a close look at some snowflakes, and then go inside to make their own snowflakes out of paper.
Caillou wants to play hockey with Billy and the other big kids. He goes with Daddy to the store to get the equipment he needs, but he finds he just can’t keep up with the big kids. After Daddy gives Caillou his old hockey sweater - which is way too big for Caillou - he tells him that if he keeps practicing he’ll be really good by the time he grows into the sweater. Caillou goes to Leo’s house to practice his hockey skills and dream about the future.
Mommy can’t find Caillou’s toboggan for the playschool tobogganing trip and Caillou is certain he’ll miss out on all the fun. Miss Martin tells him that a cardboard box slides just as well as a toboggan on snow, so he decorates a box to look just like a bobsled. Once they get to the hill his bobsled box works just as well as all the other kids’ toboggans and he has a grand time after all.
Clementine’s big brother Billy has a new drum set and is having lots of fun playing as loud as he can. He won’t let Clementine and Caillou play his drums though, because he says they’re not grown up enough. The two friends set out to prove him wrong, and once they put on their ‘grownup costumes’ he finally relents and lets them play. Caillou pretends he’s a rock and roll drummer playing a big drum solo!
Caillou and his friends are very excited when a real marching band goes by the playschool. They decide they want to be in a marching band too. The kids find some makeshift instruments in the classroom, and Emma makes them matching band hats. After a shaky start, Caillou leads the others by beating on his drum and they march around the schoolyard like a real marching band.
The playschool is having a talent show and Caillou wants to sing a song, but Clementine beats him to the punch, picking the exact song he wanted to sing. When it turns out she’s having trouble remembering all the words, Caillou suggests they work together and the resulting song-and-dance routine is the hit of the show!
Caillou has to decide on a nice surprise to bring to playschool for Show and Tell. The only problem is, he can’t decide between his toy dinosaur Rexy, his kite, or his toy firetruck. However, when Rosie proves to be the best at surprising everyone, Caillou decides to bring his little sister for Show and Tell.
Grandma shows Caillou a simple magic trick, which makes him decide to be a magician. After finding a suitable costume, he practices a new trick - making Rosie disappear! When the time comes to show Mommy and Daddy their trick, Caillou finds that making Rosie reappear might be a challenge, especially when Gilbert gets in the way!
Caillou wants to play castles and dragons, even though Gilbert isn’t very keen on playing the dragon. Mommy asks him to share and play nicely with his sister, so Caillou and Rosie build their very own castle out of empty cardboard boxes. When Gilbert doesn’t want to be the dragon, Mommy and Daddy volunteer for the part and everyone has lots of fun playing make believe.
Caillou is playing with Jeffrey and Jason when he gets accidentally pushed down. He is a little upset about it until he realizes it was an accident. Since it's so hot out Daddy treats them to ice cream and Caillou imagines he's down at the cool cool south pole playing with the penguins!
There's a new girl named Lee Wun in playschool, but she's so shy she won't talk to anybody. Miss Martin brings in a fish tank to show the class. After imagining he's a tiny deep sea diver swimming in the fishtank, Caillou discovers that Lee Wun knows a lot about fish! Encouraged to tell the others what she knows, Lee Wun is able to start making new friends.
The whole family is on the way to the beach but accidentally end up on a trail through a swamp. Caillou is disappointed, he doesn't think a swamp could be very interesting, until he takes a closer look at the creatures who live there. He imagines he's in the Bayou searching for alligators.
Caillou is playing with the fridge magnets and learns lots of things about them. About what they stick to and what they don't stick to - like Gilbert! He even imagines himself as a human magnet superhero. In the end Caillou is able to apply what he's learned and uses a magnet to help Daddy retrieve a metal peg from behind the workbench.
The whole family goes on a trip to the natural history museum to look at the dinosaurs. Caillou is really enjoying himself looking at the skeletons and learning about the different kinds of dinosaurs. When he momentarily loses the others he knows enough to stay put until Mommy comes back and finds him. And when he realizes he's left Rexy somewhere he learns about the lost and found, and retraces his steps until he finds his dinosaur friend.
Caillou wants to play with both his friends Clementine and Xavier in the playschool playground. Unfortunately Clementine wants to play bears and Xavier wants to play astronauts, and a little argument ensues. At story time Miss Martin tells them more about spaceships and astronauts and Caillou imagines he's zooming around the galaxy exploring stars and planets. Back outside Caillou makes up a new astronaut and bear game so everyone can play together.