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.

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.

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.

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.

Eddie lives so far away from Chuggington that he just can't seem to get into work on time. After getting into trouble with Morgan yet again, he decides to sleep at the depot, to be sure to be on time. But Calley's emergency callouts keep him awake all night, and he oversleeps. Late again! Hodge and the trainees try to find a new home for Eddie in Chuggington.

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 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.

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.

Zephie admires the 'big' chuggers, and wants to pull freight just like them. Brewster is dismissive when she offers to help him - you have to be big and strong to do the things he does. When Zephie overhears Brewster being given his jobs for the day, she decides to do some of them for him. Then he'll see just how good she is at pulling freight!