- "You are International Rescue, are you not?"
— The Hood attempting to persuade Scott to rescue him
The Mechanic finally completes Project Sentinel, and aims to test its destructive capabilities by making the Hood his first target. As the International Rescue team scrambles to save an old foe, Brains embarks on a dangerous mission to neutralise the Mechanic once and for all.
- Scott Tracy, Alan Tracy - Rasmus Hardiker
- Virgil Tracy, Gordon Tracy
- John Tracy - Thomas Brodie-Sangster
- Kayo - Angel Coulby
- Grandma Tracy - Sandra Dickinson
- Brains - Kayvan Novak
- Lady Penelope Creighton-Ward - Rosamund Pike
- Parker - David Graham
- Colonel Casey - Adjoa Andoh
- The Hood - Andres Williams
- The Mechanic - Chris Jarman
- Biker - Adjoa Andoh
International Rescue Equipment Used Edit
- Thunderbird 1
- Thunderbird 2 (Module 4)
- Thunderbird 4
- Thunderbird 5
- Thunderbird Shadow
- FAB 1
Non International Rescue Equipment UsedEdit
- This is the only episode Colonel Casey makes an appearance in the latter half of Season 2 following a lack of plot involvement with the GDF.
- The Hood was arrested for the second time, however it appears the Chaos Crew had hijacked the GDF flyer, allowing him to be free.
- This is the first time The Mechanic was arrested, however, it wasn't initially his fault for his actions.
- This is the first time The Hood is seen onboard a Thunderbird.
- This episode is the first to show Thunderbird 5's Space Elevator being able to act independently from Thunderbird 5 and can be used as a (very small) space vessel.
- This episode hints that The Mechanic will become an ally to International Rescue, and possibly shining light on certain mysteries.
- This is the first episode to directly use the name one of the main characters in it's title, i.e. "Brains", and the "Brawn" part of the title could be attributed to The Mechanic as he is shown to have large muscles, and of course, the episode focuses on the two of them.
- This episode marks the first appearence of the Chaos Crew.