Air date: September 19th, 2018 (UK)
Merlin comes to Sodor from the Mainland for the first time. He thinks that when he shuts his eyes nobody can see him. Percy hears everyone talking about the 'invisible' engine and wonders why he hasn't seen him. But how can you see an engine that's invisible?
Tropes:
- Accidental Misnaming: Merlin calls Sodor "Sonar", like he did in Journey Beyond Sodor.
- A Day in the Limelight: For Merlin. Percy also has his first proper focus episode since season 19.
- An Aesop: It's important to know what's real and what's not, but playing make-believe can still be fun.
- Ambiguous Situation: It's unclear as to why Merlin was sent to work on Sodor. He delivers steel to Brendam Docks, but that's it.
- Bittersweet Ending: At the end of the episode, Percy hears Trevor's new whistle sound and thinks it belongs to the invisible engine. He does see Merlin, but Percy doesn't know that Merlin is the invisible engine, and the episode ends on that note.
- The Bus Came Back: Merlin, a character who debuted in Journey Beyond Sodor, returns in this episode. They even managed to get Hugh Bonneville back to voice him.
- Call-Back:
- Merlin and Thomas are still friends after Journey Beyond Sodor, and Merlin still thinks that the Island of Sodor is called "Sonar".
- Door-Closes Ending: The episode ends with Percy's shed doors closing in the camera's focus as he goes to sleep.
- Imagine Spot: Percy has one where an invisible engine is pulling Annie and Clarabel, and they reveal that they can turn invisible too.
- Invisibility: The main theme of the episode.
- Jerkass: Gordon, for telling the other engines that he wishes they would turn invisible so he can get some sleep.
- Visible Invisibility: Merlin is still convinced that he can turn invisible. Cranky, Carly, Trevor, and the rest of the current Steam Team (Thomas, James, Percy, Gordon, Emily, Nia, Rebecca) all can still see Merlin, but play along with it and pretend he really is invisible.
