Air date: September 8th, 2016 (UK)
One early morning, Thomas pulls into Brendam Docks and greets Salty and Cranky. Unfortunately, Diesel is not feeling quite so friendly, and he bashes Thomas forward. Diesel thinks that all diesel engines should be rough and tough, calling Salty a "big softie" when he disagrees.
Later, Thomas whistles hello to Percy, who is having a wash before he starts work. Diesel then pushes Percy forward too, and takes his place at the washdown. Thomas tells Diesel that he should be nice if he wants to make friends, but Diesel replies that his friends, Arry and Bert, already like him because he's rough and tough.
Later that day, Thomas is still thinking about Diesel when he sees him parked up ahead, talking softly to some ducklings. Thomas is surprised: he has never seen Diesel being so sweet and gentle before. Thomas can't wait to tell the other engines how much of a softie Diesel is being, but Diesel begs Thomas not to tell in case the engines laugh at him. So Thomas promises not to tell as long as Diesel keeps being friendly towards the other engines.
Diesel tries hard to act friendly, and greets each engine as they pass by, much to their confusion. At Knapford, Diesel greets Edward a good morning, when he notices Arry and Bert watching him. Not wanting his tough reputation to be spoilt, Diesel quickly begins to make fun of Emily, which makes Arry and Bert chuckle. Thomas then pulls up behind Diesel and reminds him of his promise. So Diesel apologizes to Emily and quickly hurries away.
But Diesel can't help returning to his old ways. He rolls slowly along in front of James and Gordon, which makes them cross. Thomas again reminds Diesel of his promise by making quacking noises at him, so Diesel reluctantly lets James and Gordon through. Later, Diesel biffs and bashes trucks in front of Arry and Bert, declaring that he is rough and tough. Thomas once again quacks at Diesel, but Diesel has had enough of trying to be nice. So Thomas cheekily tells Arry and Bert to follow him, and they set off towards the ducklings, with Diesel behind.
Diesel begs Thomas not to tell, but Thomas reminds Diesel that he has broken his part of their agreement. As the engines approach the duckpond, Diesel sees the duck family crossing Thomas' line, and calls out to Thomas to stop. Thomas screeches to a halt just in time, and the ducks continue crossing. Thomas praises Diesel for being a hero and a softie. Diesel declares that he is not a softie, but then Arry and Bert begin to make a fuss over the ducklings just like Diesel had. Thomas realizes that all three of the diesels are big softies at heart when it comes to ducklings.
This episode contains examples of:
- An Aesop: It's okay to show your soft side.
- The Bus Came Back: This is Arry and Bert's first speaking role since Season 16, having made only Freeze-Frame Bonus cameos in the interim.
- Cold Turkeys Are Everywhere: Diesel finds it hard to be nice to the other engines, especially when he's around Arry and Bert.
- Funny Background Event: After Diesel bumps into Percy, Diesel's driver snatches the broom from Percy's driver.
- Hidden Heart of Gold: Diesel doesn't want Arry and Bert to see his soft side in front of the ducklings. Of course, Arry and Bert turn out to have a soft side.
- Insulted Awake: Diesel wakes up a truck by biffing it.
- Irony: Of all the animals Diesel has a Cuteness Proximity towards it's ducks.
- Rhymes on a Dime:
- Diesel's "Hard as nails, always gruff, a diesel should be rough and tough!"
- In the ending, Thomas says to Diesel, Arry, and Bert, "You try to be tough and play the part, but when it comes to ducklings, you're all softies at heart."
