Wilson and Koko are having loads of fun racing each other - until Wilson damages his wheel! He's scared of going to the repair shed to get it checked out, so he tries to put on a brave face and ignore the problem - despite Koko and Brewster's protests. When he gives Felix the Farmer and his churns of fresh cream a ride to the market, Wilson's condition worsens.

The trainees are heading for a lesson with Dunbar in the training yard when an underground tunnel catches Koko's eye. She wants to explore it but Vee says she isn't ready yet. Dunbar is called away from the lesson about switching tracks before they barely get started. With time on her wheels, Koko decides she's going to see where that tunnel goes.

The trainees are playing hide-and-seek - and everyone has to admit that Wilson is the best hidey-chugger ever! The trainees' game is interrupted for a lesson: learning how to do different emergency stops with mud, leaves and water on the rails. Wilson is in heaven, as he likes nothing better than getting dirty!

When Harrison breaks down, Koko volunteers to replace him on the night shift, determined to make the fastest run ever. But Vee insists that Wilson and Brewster go too, despite Koko's protests that Brewster will slow them down. Koko races off, teasing Brewster about being a 'slowcoach.' Suddenly she shudders and slows to a stop and Brewster and Wilson overtake.

Dunbar has some news, he's leaving Chuggington to do some traveling. Brewster is very sad to see Dunbar go so makes him promise to say goodbye before he leaves. Skylar is going to be the trainees new trainer, he's fresh from the training academy. He starts with some crane training and explains it's all about focus and flow.

Wilson is determined to get his Animal Transportation badge by taking Ebo the elephant to his new home in the Safari Park. But the naughty elephant has other ideas! He causes mayhem by throwing fruit and grabbing onto low hanging branches. To top it all, he uses his trunk to uncouple his car and escape! Poor Wilson chases after the mischievous elephant, who leads him down an overgrown track.

Koko challenges Wilson to see if they can stay awake all night! Morning comes, and Wilson declares himself the winner - just as Vee gives him a job for the day: he's going to be collecting the mail and taking it to the sorting office. While Koko sleeps in, poor Wilson struggles to keep his eyes open.

Koko challenges Hodge to a competition: whoever does the most jobs that day wins! But it has to be a secret. Hodge can't even tell Eddie. Hodge hurries off, eager to get started. Meanwhile, Eddie's having a little trouble tuning the electric guitar he found and wants to fix it. Hodge, desperate to win the competition, runs Eddie all over town instead, doing jobs that don't really need doing.

It's time for the annual Chugger Championship Race - and speedy Koko is sure that the big, shiny trophy is hers! She's so determined, she spends hours practising and doesn't have time for anything else. Wilson thinks that the race is more important to her than her friends and the two of them fall out. When Wilson breaks down during the race, Koko must choose whether to help him.

Koko finds a lost puppy and wants to keep it. Convinced she can look after him and practice the new task - delivering newspapers - Koko soon runs into trouble. Zoomy needs lots of attention, food and walks. With all the extra work, Koko will never be able to get the hang of the throwing arm to deliver the newspapers into their boxes!

The trainees are going to be fetching and delivering building supplies today. As they're working, Brewster sees a builder flip his clipboard in the air. Wow! He's never seen anyone do that before! Wilson wonders what's so special about that. Brewster introduces Wilson to his new hobby: people-spotting. Before long, Wilson is hooked too, and the two trainees get a bit competitive.

A storm has left the Safari Park in a bit of chaos, and some animals have escaped! Emery teases Brewster, saying one of the escapees is a dragon. So when one of the fugitives - a golden bell frog - makes his home in a tunnel that amplifies his distinctive 3-note croak into a mighty roar, the trainees are convinced that Emery is right!

The trainees are taking their passenger test. If they pass, they'll be able to carry passengers all on their own. Brewster and Wilson are a little nervous, but Koko is confident - after all, she's a passenger train! Mr. Simkins, from the Ministry of Chuggers, arrives to examine them. His 'jiggleometer' will tell him whether or not the trainees are riding smoothly. Koko volunteers to go first. Unfortunately, just as she starts, Simkins coughs and sets the machine off with a deafening beep. Koko jumps and Simkins gets thrown across the carriage. He fails Koko and, despite her protests to be given a second chance, is unmoveable. Broken-hearted, Koko goes off to the recycling yard and pours her heart out to Irving. Irving remembers Simkins of old and intervenes - reminding him of a similar situation in his own past. Simkins relents and gives Koko another chance! This time, without the jiggleometer, Koko passes with flying colours!

Zephie has never worked in the Safari Park before, so she's excited to be taking the vet, Dr. Gosling, to give the animals their checkups. Emery teases her, saying she'd better watch out for the monkeys. They might pull her wipers or steal her bell! Zephie gets worried. When Dr. Gosling says he'd like to start with the monkeys, she asks if they can do the giraffes and elephants instead.

Mtambo's in a bit of a rut giving the same old tours everyday in the Safari Park. He wants some adventures in his life so that he has new stories to tell. One of Mtambo's passengers, Freddy, says that he's about to head off on a jungle expedition. Freddy asks Mtambo to watch his camera gear while he goes to the souvenir shop. Mtambo makes up his mind to ask Freddy for a job when he returns.

The trainees are doing a sign-reading exercise. If they work as a team and follow the signs correctly - there'll be a wonderful surprise at the end of it. The trainees start off together, but Koko and Wilson quickly lose patience with Brewster - he's so methodical, that it's slowing them up! The friends have a bit of a falling out.

Wilson has been given the important job of bringing the refrigerated ice cream cars from the ice cream factory to the Ice Cream Tasting Fair. The refrigeration cars are heavy, so he'll have to take them one at a time. Wilson makes the first trip successfully, but when his hero - cool ice cream chugger Frostini - offers to give him a tour of the factory, he forgets all about his important job.

Wilson is assisting Frostini as he creates a new flavour for the mayor's banquet: Chugstastic Chewy Cheesecake! But they discover that the mayor's wife is allergic to cheese. Frostini will have to come up with something else by tonight! Wilson tries to help, but ends up causing the mixing machine to explode covering everything in ice cream. Annoyed, Frostini sends Wilson to the chugwash.

The chuggers have often told Emery that he is so funny, he should be on the stage. So when a TV crew comes to make a documentary about Chuggington, Emery sees his chance for stardom. The TV crew love how he jokes about the other chuggers - and they decide to have him do the narration for the documentary.

Wilson and Brewster are sent to get stone from the mountain quarry. Brewster is in a hurry to get the job done, so that he can get back and practise some new moves in the training yard with Koko. For once he doesn't slow things down by asking questions, and he doesn't hear Dunbar warning them to be extra careful on the way back, as going downhill with a heavy load is harder.

Part of the track is out, and there's chaos in Chuggington! Vee needs Eddie to repair the track - but he's late for work again. Hodge prepares the electro-magnetic crane and the replacement track so they will be ready to go as soon as Eddie arrives. Wilson persuades Hodge that he could do the repairs by himself and save Eddie from getting in trouble. Hodge doesn't think so.

Koko has her first big solo delivery job, picking up timber and delivering it to the paper mill - that is if Old Puffer Pete gets out of her way! In spite of Pete's admonition to 'take it slow and steady,' Koko speeds toward the timber yard, nearly ploughing into a family of squirrels! On her return she encounters the squirrels again - but this time she has to make an emergency stop.

Brewster delivers some feed to the Safari Park, and hurries back to practice today's task - picking up mail sacks - unaware that he has a monkey stowaway onboard! Back at the depot, someone - or something! - is causing mayhem. Methodical Brewster's questioning mind comes in very handy when he turns detective.

The trainees are learning how to use ice-cream cars today, and will be trying for their Ice-Cream badges. The great Frostini is going to test them on their skills. When Wilson's car breaks down, Puffer Pete comes to the rescue, pulling out his old steam driven ice cream wagon from the back of the rolling stock store - where it has sat for thirty years.

Koko is yearning for adventure - and she just might get it, as today the chuggers are making deliveries out of town. But Vee asks Old Puffer Pete to accompany them - and he's so SLOW. They always have to wait for him to catch up - and he's always letting off those embarrassing bursts of steam! During their travels, they come across a mysterious old spur track. Pete tells them it leads to Old Chuggington, which is now a ghost town. The trainees decide to explore the old town on their own and get helplessly, hopelessly lost. When Wilson accidentally sets off the old Chuggington Central Whistle, Pete puffs his way through the maze of tracks to investigate. He rescues the youngsters and takes them on a fascinating tour of the old town, which he still knows like his own pistons! The trainees realize that Pete isn't such a fuddy duddy after all and there's a lot that they can learn from him.