Thomas, a young tank engine with a shiny blue exterior, clickety-clacks his way through daily work and fun adventures alongside his locomotive friends on the island of Sodor.
After accidentally derailing Gordon, Thomas makes a promise to deliver Gordon's cargo to Whiff's Recycling Plant while racing with Diesel to get there first.
Thomas is excited about a rocket launch happening at Brendam Docks. When he's tasked with delivering a battery, he puts it off to help the other engines deliver the rocket pieces.
Thomas suggests playing secret agents along the way to help Percy forget about his fear of the dark when Percy must deliver a new light bulb to the lighthouse at nighttime.
At Knapford Maintenance Yard, Thomas constructs his ideal obstacle course. However, none of the trains can do the course because Thomas only built it for his abilities.
Annie and Clarabel have a night-time delivery, so they need to get to their destination that day well-rested. Thomas volunteers to take them but must remain quiet.
Thomas loves to race Kana. He uncharacteristically wins when her power goes out. Unable to move fast, she may not make it to her destination before sunset.
It's Thomas's job to deliver a giant wooden dragon at the Medieval Faire at Kirk Ronan. The other engines want a turn, so they all compete to catch the dragon.
Thomas finds a map to the special Crystal Locomotive landmark in the Crystal Caves and forms a Big Adventure Club to go explore.
Thomas is nervous about taking a delivery to the mine so Percy gives him his lucky bell to take along. However, Thomas is careless with the bell and it falls down the mine.
When Sandy learns about a shipment of sand that needs to be delivered, she is determined to help. But her size means she can't help Thomas tow the sand.
Thomas is disappointed to be paired with Diesel for a delivery instead of his best friend Percy.
After volunteering to handle a herd delivery, Thomas and Percy struggle to keep the cows together when they keep wandering off alone.
Nia is excited to see a concert, but when she gets stranded and cannot attend, Thomas decides to take the concert to her.
After learning about Backwards Day, where everything is reversed, Thomas and Percy cause trouble when misunderstandings lead to mistakes.
Thomas and Kana spot a rainbow and decide to find out where it leads, eager to find the prize that's always at a rainbow's end. But, as they chug along, the rainbow keeps moving.
Nia has to deliver a giant balloon float for a parade, but it's a really windy day and the balloon breaks free and floats away!
Thomas helps Percy look for the parade flag he lost just before the big event.
Kana gets frustrated when she keeps running out of power, but the idea of a mystery scavenger hunt perks her up.
Thomas imagines he is a hero, and he is going to help Nia deliver a movie screen in perfect condition.
Percy is not sure he is comfortable spending a night away from home during a delivery with Thomas and Nia.
Thomas and Percy attempt to surprise Diesel, but when things do not go as planned, the friends still manage to cheer up Diesel.
Thomas assists Nia on a delivery to the beach in Norramby, and he takes the lead saying he knows a shortcut, but his memory is not as good as he thought.
When all the trains but Thomas get deliveries, he's left to spend the day alone. He finds a new friend in a boxcar, taking it around his favourite places.
Diesel makes a comment about Thomas not being number one anymore, which makes him doubt his abilities when his number gets covered in paint.
When Thomas, Kana and Nia find out Percy wants to go on a rollercoaster, they try to find a way to make it happen.
A power outage causes problems all over the island, but Thomas is determined to show passengers some scenic views.
Thomas gets jealous when Yong Bao visits Sodor, so he challenges Yong Bao to a bunch of bravery challenges.
Thomas and Percy are assigned to deliver a submarine to Vicarstown, but they have a communication breakdown that makes things difficult.
Thomas and Percy must find a way to safely transport their delicate cargo of eggs and baking ingredients to Vicarstown for their bake-off.
A series of mistakes causes Calliope to break down on the way to the annual Norramby Beach Carnival and the other engines must come up with a creative way to fix the problem.
Thomas and the other engines plan their delivery of some newly discovered dinosaur bones, but they must find an efficient way to transport them in the correct order.
Thomas offers to help Gordon make an important delivery, but Gordon keeps questioning Thomas' every move.
Thomas accidentally breaks a light he was taking to the Sodor Festival of Lights, and he learns that being honest is the best way to be the top engine.
Thomas struggles to stay still while his new paint job dries because he feels like he is missing out on fun.
Nia tries to show Thomas and Diesel the unique beauty of Sodor, and they take some of its beautiful plants to redesign a plaza in Vicarstown.
When Thomas' whistle suddenly stops working, he learns that he doesn't need his whistle to still be himself.
Thomas and Percy laugh at each other over embarrassing moments, which causes them to get into a fight that could destroy their friendship forever.
Nia has volunteered for a big day of deliveries and is determined to make the perfect plan to get it done.
Yong Bao is leaving Sodor, and all the other trains want to get him Something To Remember them by when he returns to China.
When a big storm approaches, Thomas and company must complete a week's worth of deliveries by the end of the workday whistle.
While the trains are setting up for the Vicarstown Fall Festival, Thomas is feeling down about the end of summer and the changing weather.
Percy prepares to deliver mail on Halloween, but he feels afraid because the legendary Ghost Train is said to appear on the spooky holiday.
Thomas learns the importance of not touching items that aren't yours after he throws away Diesel's favourite oil can by assuming it is trash.
Percy and Diesel prepare to play a game that consists of surprising the other players, but even though Diesel helps create the game, he struggles to play it.
As Thomas and Diesel race each other across Sodor, they take things a bit too far by putting an important delivery at risk for a simple competition.
Percy announces he is giving up his Ghost Scaring Machine, as he is too old for it now. However, it soon becomes clear that the machine is good for more than just scaring ghosts.
Thomas feels excited after he discovers a cowbell on the side of the tracks, but trouble arises when his friends also want to play with the cowbell.
When Sir Topham Hatt's Hat blows away in the wind, Thomas and his friends race around Sodor, trying to catch it.
Nia is planning a party to celebrate the anniversary of her arrival on Sodor. But when she tries to to talk about it, she finds that her friends are too busy.
Thomas carries a famous musician across Sodor, and in the process, Thomas gains a new appreciation for being his normal engine-self.
When Skiff gets a crack in his hull, Thomas needs to move him overland to Harwick for repairs, but Skiff doesn't feel comfortable on dry land.
When Nia suggests adding a song to spice up Sir Topham Hatt's new bench unveiling, he calls upon her to write a song for the ceremony.