- "I am the Mechanic. And if your Thunderbird comes any closer, I'll break it as well."
— The Mechanic
A geological survey team looking for Scandium ore gets trapped when a huge earth-breaking vehicle, controlled by a villain known only as the Mechanic, causes them to fall into a narrow crevice. As Thunderbirds 1, 2 and Shadow are dispatched the Mechanic takes out several GDF fliers. Thunderbird 2 is also attacked from the Earthbreaker and has no choice but to crashland back on Tracy Island. Meanwhile, Lady Penelope and Parker visit the Hood in Parkmoor Scrubs prison to find out more about this mysterious new villain.
- Scott Tracy, Alan Tracy: Rasmus Hardiker
- Virgil Tracy, Gordon Tracy: David Menkin
- Kayo: Angel Coulby
- John Tracy: Thomas Brodie-Sangster
- Grandma Tracy: Sandra Dickinson
- Brains: Kayvan Novak
- Lady Penelope Creighton-Ward: Rosamund Pike
- Parker: David Graham
- EOS: Teresa Gallagher
- The Hood: Andres Williams
- The Mechanic: Chris Jarman
- Colonel Casey: Adjoa Andoh
- Baines: "Wow, we could have ourselves another gold rush here, Hutch!"
Hutch: "Except it's Scandium ore, not gold."
Vic: "Ten times as valuable though, KA-CHING!"
- Gordon: "Anything Alan and I can do?"
Scott: "Just hold down the fort."
Alan: "We can build one right here out of sofa cushions." (Scott, Virgil, and Kayo look at him skeptically) "Or not."
- Kayo: (Confronting the Mechanic) "You'll be pleased to hear our engineer is impressed by your handywork."
The Mechanic: "He's a clever one, but not the only one with 'brains'."
- Baines: "Thank you, International Rescue."
Vic: (sighs) "I sure hope not. I never want to be in the kind of fix where I have to see you people again. No offense."
Scott: (chuckles) "FAB."
International Rescue Equipment Used
Non-International Rescue Equipment Used
- Main article: Earthbreaker/Transcript
- Voice artist David Graham returns to voicing guest characters, having done the same on the classic series.
- Thunderbird 2's electromagnetic grabs are severed and destroyed.
- The circumstances of Thunderbird 2's forced landing in this episode reflects the crash-landing in the original episode Terror In New York City, except that its damage in the original episode was the result of a misjudged attack rather than the deliberate assault it was in this storyline.
- It's the first time the boys don't just sit or stand around the holographic interface from the coffee table, in fact Gordon and Alan are fighting each other with the couch cushions while the rescue is taking place to amuse themselves.
- This episode marks the second time that the Hood has not been disguised to any extent.
- Sonar Vehicle D103 is named after the D103 Airliner from Alias Mr. Hackenbacker.
- When Thunderbird 2's VTOL engines are attacked by Air-Mechas, its Module is missing for a few quick seconds.