International Rescue must save a hydro-dam after the Mechanic sabotages it. Scott crawls inside to rescue the crew while Virgil and Gordon attempt to seal a growing crack in the dam.
- Scott Tracy, Alan Tracy - Rasmus Hardiker
- Virgil Tracy, Gordon Tracy - David Menkin
- John Tracy - Thomas Brodie-Sangster
- Kayo - Angel Coulby
- Brains - Kayvan Novak
- The Hood - Andres Williams / Teresa Gallagher (as Captain Foster)
- The Mechanic - Chris Jarman
- GDF Soldier - Teresa Gallagher
- GDF Lieutenant - Chris Jarman
- Turbine Room Chief - Kayvan Novak
- Turbine Room Mate - Thomas Brodie-Sangster
- Dam Operator - Angel Coulby
Gordon: "I just have one question. If you drop me off, how are you gonna get the pods out?"
Virgil: "Glad you mentioned that. Better hold on to something."
(The module is lowered and it opens.)
Gordon: "Hey, what are you..." (Thunderbird 4 falls out of the module, skips along the water, and sinks in.) "Okay, that was awesome, but, a little more warning next time?"
Virgil: (laughs) "It was Alan's idea."
Alan: (chuckles) "Sorry, Gordo!"
Gordon: "By the way, this stuff washes off, right?"
Virgil: "Uh, no, that's the point."
Gordon: "Oh, just checking."
Virgil: "You didn't get any on Thunderbird 4, did you?"
Gordon: "Let's focus on the positive, shall we? Like we saved the whole town today!"
Gordon: "Does he looks angry? He looks angry. It's about Thunderbird 4, isn't it?"
Brains: "It's not about Thunderbird 4, Gordon. This is much, much worse."
Gordon: "Good, I mean, oh no!"
International Rescue Equipment Used
- Thunderbird 1
- Thunderbird 2 (Modules 4 & 5)
- Thunderbird 4
- Thunderbird 5
- Thunderbird Shadow
- Gecko Pod
Non International Rescue Equipment
- This is the first time another International Rescue craft (Thunderbird Shadow) has carried one of Thunderbird 2's modules (no. 5).
- This is the second time the Gecko Pod has been used, which was first seen in Weather or Not.
- This is the first time Alan both pilots and co-pilots Thunderbird 2 in this episode.
- This makes the first reference to Project Sentinel, an old project of the Hood's that was abandoned as being too extreme even for him but has now been taken over by the Mechanic.
- This is the first time the GDF acted with International Rescue on Earth without Colonel Casey.
- Captain Foster is a reference to Captain Foster in the film Thunderbird 6.
- This is the only episode when the Mechanic utilises all three different types of Mechas.
- This is the only known instance where Module 4 was shown carrying equipment besides Thunderbird 4 (two additional Pods).
- In the opening shot, a gap where there is no mountain can be seen on the left.
- When the Scorpion Mecha is in the same tube as Scott, and it exits the tube, it goes out a different way that Scott got in.