Sidney has to go and collect Percy's new wheels, but his memory is not very good. Thomas suggests that Sidney to make up a song to help him remember. By mistake, he thinks his job was to pull passengers to the Docks, but after talking with the Fat Controller, he gets the wheels to Percy in the end, and the two laugh at the Steamworks.

Philip thinks that Toby is a boxcab just like himself and wants to become friends, but Toby is not so keen on doing the same thing as Philip and finds him rather persistent and overwhelming, by having a race to the Ffarquhar Quarry.

One morning, Gordon's firebox needs to be cleaned out, making him late to pull the express. As a result, the Fat Controller gives Henry the job of pulling the express. Passengers start saying that Henry takes the express even more gently than Gordon does. Meanwhile, Gordon has had enough of pulling Henry's goods trains, and leaves his Troublesome Trucks at the Blue Mountain Quarry. That night, Gordon is told to take the Flying Kipper, but he refuses to do so, prompting Henry and Thomas to trick him into doing it. So Gordon sets out to pull the train. When he gets back in the morning, Sir Topham Hatt tells him he can go back to pulling the express again.

"Devious" Diesel is known to be mean against the other engines on Sodor, and that is how his diesel friends like it. One day, Thomas spots Diesel being friendly with some ducklings, and threatens to tell everyone if he is mean. Throughout the day, whenever Diesel is about to get devious by calling Emily names, blocking James' and Gordon's lines, and biffing and bashing the Troublesome Trucks very hard in the Shunting Yards, Thomas warns him with a "quack quack quack". As Arry and Bert find him suspicious, Thomas shows the ducklings, but the two diesel twins find the ducklings cute and adorable, making Diesel think he can after all be nice.

Thomas has trouble with the Troublesome Trucks yet again in the yard. When Samson arrives with a goods train, his brake van, named Bradford, sees Thomas and offers to help. Bradford puts the Troublesome Trucks in their place easily. Every other engine thinks Thomas is lucky to have a brake van like Bradford. However, after being delayed at the Blue Mountain Quarry, Thomas does not feel Bradford means any good. After delaying Whiff, Henry, and many other of his friends, Thomas goes without Bradford for one day, even though he shouts at Thomas that he needs to talk with him. Thomas collides and derails Percy's trucks at the other side of Gordon's Hill. When the Fat Controller hears of the accident, he scolds Thomas for not using a brake van and tells that following the rules and staying safe is more important than being on time. Bradford tells Thomas and his friends that he is sorry for the troubles he caused lately, and that he is leaving to go with Samson back to the Mainland again. Everyone is happy that Bradford is leaving Sodor for a while, including the Troublesome Trucks.

Samson comes to Sodor to help out with bringing stone from the Blue Mountain Quarry. At the quarry, he asks Sir Handel about some extra trucks on a siding. Sir Handel explains that they are indeed meant to be brought to the docks, but that Samson should come back for them later. While attempting to go up Gordon's Hill, Samson gets stuck and tries again. Thomas helps him, and they get some extra help from Paxton. The Fat Controller is not pleased with the delay, and Samson tries to be more careful, by only bringing one truck and a brake van.

Despite being different from each other, Ryan and Daisy work together on the branch line between Harwick and Arlesburgh. One day, Ryan arrives at Arlesburgh West to see the Fat Controller. He tells Ryan that he is giving Ryan and Daisy extra duties. Ryan later tells Daisy about her mail run, but she says Ryan would do it better, so Ryan takes the responsibility for the mail. However, when he is late to help Toby with the stone deliveries to Arlesburgh, it really gives Ryan more and more to do and causes more delays as well. Another day, Ryan almost collides with Duck, and he also hurries to the quarry with his coaches and the passengers do not like it at all. The Fat Controller is cross with Daisy, but the problem is solved when Daisy finally helps out by doing her own work and Ryan's work.

James is known to show off too much, and he always wants to be the center of attention. One day, he goes too far with his boasting and the Fat Controller takes his coaches away. James is left in the shed. Later that day, he promises to behave and is given a job, but he is not happy when he discovers that it is garbage trucks. He is cross and goes around in a sulk, taking too long getting from point A to B. At Brendam Docks, James is teased again, until it makes him laugh. From that day on, he changes his attitude and does whatever work he needs to, but another engine will always alert him when he starts getting grumpy again.

A heavy storm is arriving at the Island of Sodor. At Arlesburgh, Skiff's new captain, Joe, checks that everything is secure. Duck and Oliver are just finishing their passenger runs, and tease Skiff for being a little rail boat. Captain Joe reassures Skiff they just said this because they are worried about him. When Joe checks over the pirate ship, Skiff is suddenly blown away down the track, and crashes into a tree that has fallen over onto the track. He manages to get himself free and waves his sail, preventing Duck and Oliver from crashing. The following morning, they have decided that Skiff deserves a gift, and together with Sir Topham Hatt and Harvey, they cheer for Skiff, who they reckon is the bravest little rail boat they have met.

Sir Topham Hatt gives Daisy a special, to bring some entertainers for a performance. Daisy is excited, and boasts that the entertainers would choose a railcar like her. Engines like Thomas, Duck and Oliver are not that surprised, and neither is Ryan, who says that sheep still prefer tank engines. The next day, Daisy does not take the usual passengers with dogs, ice cream, or sand, and when Stafford is about to couple a truck up to her at Knapford, Daisy refuses to pull the truck and leaves without it with the two entertainers inside her. Daisy finds out that the entertainers are puppet show entertainers when she arrives at Harwick station. Sir Topham Hatt arrives, and Daisy realizes she has let everyone down. She comes up with an idea, which saves the entire situation. Not liking it at first, she uses one of her windows for the stage and she eventually likes it.

Percy still remembers the time he raced against Harold the Helicopter. One day, he is bringing letters to Santa, and thinks that Harold is calling him slow and out of date again, and decides to not listen while he tries to make up for lost time due to the snow. Not realizing that Harold is trying to warn him, Percy ends up in a blocked tunnel of snow. Harold offers to take the mail to Hiro, which Percy accepts. Thinking Harold is bothering him, Hiro says that Percy never arrived. Harold explains, as Hiro comes to a stop. The following day, Percy looks after Harold, and finds him on the other side of the Vicarstown Bridge. Harold says he has run out of fuel, and Percy gets some fuel for him, saying that friends are to help each other, and it will soon be Christmas.

Snow has arrived early to the Island of Sodor, and Donald and Douglas work together to clear the tracks. While at a junction, they have a choice: to clear Thomas' branch line or clear the track to the Search & Rescue Centre. While Douglas suggests the branch line, Donald wants to clear the track to the rescue centre. After clearing the track there, they head back onto the mainline, but find themselves stuck behind Toby. Later, at Kirk Ronan Junction, they face another choice: Edward's branch line or the track to Ulfstead Castle. Douglas does not say anything, and the two soon pull each other's ends before Douglas is left without his tender. Thomas tells Donald about the tender, and Donald searches for Douglas. After asking Toby, he goes back to the junction, and finds his brother again. Donald later brings Douglas to the Steamworks to be repaired. Like all brothers, they sometime argue, but they always get back together again.

Daisy does not think she would ever need Annie and Clarabel when she is tasked to take care of passengers on Thomas' Branch Line while he is put on quarry duty. But one day, she does need them due to her popularity among Thomas' passengers. While out on the branch line, Annie and Clarabel say they hear a mysterious sound, which sounds like creaking. Daisy stops at a station and gets uncoupled before rushing away. After talking to the Fat Controller, she goes to the Dieselworks. The Fat Controller speaks to Annie and Clarabel, and says that two wrongs does not make a right. Another day, Thomas informs his coaches that Daisy is back to her original work, but that he is still on quarry duty, and that the Fat Controller has sent another engine to work on his branch line. The engine sent to work with Annie and Clarabel is Diesel, much to their horror and dismay.

Thomas enjoys the competition of Max and Monty but begins to question his friendship as Max and Monty mess about while working, affecting Thomas' work. Edward advises Thomas to ignore them. His suspicions prove correct as Max and Monty dump their waste on the rails, causing Thomas to derail. Luckily, Oliver the Excavator helps with clearing the tracks from the waste and Jerome and Judy help to get Thomas back onto the tracks. Max and Monty feel sorry for Thomas and Thomas tells them that he won't be racing with them anymore.

Connor boasts of being the fastest engine, but one day, he breaks down on the Island of Sodor and goes to the Steamworks to be repaired. Connor starts to get worried it will happen again if he goes too fast and after that, Connor starts to become the slowest engine on the island. They even start to worry that Connor would never go fast again, until Thomas makes Stephen tell about his past of speeds and breaking down.

James is asked to take the Mayor of Sodor and the Fat Controller to a party at Callan Castle, but has to do other jobs first and every job he does, he gets dirtier and dirtier. He finally has the chance for a washdown, but James is horrified to find a scratch on his paintwork. He goes to the Steamworks for the scratch to be painted, but leaves before the paint dries and is mortified to find leaves, twigs, and dust stuck to his paintwork, leaving Edward to take his place.

One sunny day, the tracks buckle and bend and Dowager Hatt gives the Fat Controller a new hat, which everyone calls a safari hat. The Fat Controller gets sick of everyone teasing him and tries to find a way to get rid of it. Meanwhile, a piece of glass from Whiff's garbage trucks falls out and lands on the ground causing a fire. Belle derails due to the buckled rails, meaning a solution has to be found.

Some visitors come to the island to take photos of engines. They visit the Arlesdale Railway and take pictures of the small engines, but Bert is cross that they will not take pictures of him. As they are driving, they spray Bert with mud and Bert wants to take revenge on them. He devises a plan.

Duck's driver boils an egg in his whistle, which is now clogged and makes a funny noise. The engines tease Duck about his whistle, especially Mike who says engines without whistles are improper engines. Later, he pulls passengers on the line and encounters a cow. He blows his whistle so hard that it flies far away into a field. Mike insists they look for his lost whistle, but the passengers decide to whistle for him instead.

Mike is annoyed of always being stuck behind animals, Rex boasts to the small engines about how easy wool deliveries are. The Small Controller gives him the first wool train. Willie the tractor driver accidentally drops his load of wool onto the tracks, which causes Rex to derail.

At the Steamworks, Henry is accidentally given some "glow in the dark" paint. Everyone he comes across runs away from him, thinking that he is a ghost train. The next morning, Gordon and James tease him for being scared all the time, especially of the rain, so Henry comes up with a plan to pay them back later that night.

One night, Percy is frightened by a strange sound from under the bridge at the Watermill. Toby is also worried, but Thomas does not believe it to be true, until he too hears the sound. Toby and Percy believe it is a troll telling the story of how three goats had to cross a bridge with a troll under it. The trio become terrified of passing the bridge until it is revealed the sound was only coming from a cow stuck under the bridge.

When a rail Zeppelin called Hugo comes to Sodor, everyone at first is very impressed. However, Stephen is concerned they will be replaced by engines like Hugo, making the engines worry about their future. They take their anxiety out on Hugo, making him feel unwelcome.

After word of an airship resembling Hugo spreads, Hugo feels he should be able to fly just like it. He gets some encouragement from Skiff and tries to take off into the sky like an airship on Gordon's Hill, like his non-rail aerial counterpart.

Judy and Jerome are upset that they are never taken out any more as Rocky is now the official crane of the island. Ryan, who feels sorry for them, takes Judy and Jerome out for a change of scenery. He takes them to Arlesburgh Harbour which they find boring after a while, leading to Duck and Oliver taking them around the island. Eventually, Daisy has an accident and Ryan has to find them.

Skiff hears word of a mermaid statue arriving at a museum at Arlesburgh Harbour, believing it is real. Later on when the Fat Controller and his grandchildren want to have a ride on board Skiff, he mistakes a whale's tail in the water for a mermaid and ends up dragging the Fat Controller on him to the sea in search of it. The Fat Controller does not know how to drive him, resulting in the two of them getting stuck on an island at Bluff's Cove.

Marion hears a voice behind a tree and assumes the tree is talking. She tries to tell everyone, but nobody believes her. Thomas becomes curious and investigates, only to rediscover Glynn the Coffeepot Engine. He and Percy are worried he will be scrapped, but it turns out he will be restored by the Earl.

Stephen becomes jealous of all the attention Glynn is receiving from the Earl and becomes worried he will become a stationary attraction at his new railway museum. To determine who will be the exhibit, Stephen challenges Glynn to a race.