At Heathrow Airport, Fireflash, a hypersonic plane improved by Brains, is just about to take off. In the cabin after talking to Bernard Bottomsley, Kayo calls Scott and he asks her how she feels flying home on Fireflash. After she tells him that she can’t wait, the plane takes off. Moments after Fireflash goes supersonic, it vanishes from the radar. London control contacts John on Thunderbird 5 about the incident and he contacts Scott, Alan, Virgil and Gordon about the plane.
Meanwhile, aboard Fireflash, a suspicious Kayo asks the co-pilot about why they are changing direction and contacts John with no response. In the cockpit, Captain Hanson renders the copilot unconscious with a handheld device and uses the oxygen masks to knock the passengers out. Kayo, who didn’t put on a mask, enters the cockpit and finds a cloaking device under the control panel. After tearing it out, she contacts Tracy Island and Thunderbird 5 about Fireflash being hijacked by its own captain. Scott explains that the staff at Heathrow found the real Captain Hanson in a locker and the other Hanson was the Hood in disguise.
After Scott blasts off in Thunderbird 1, London Control contacts Fireflash and the Hood answers that he has the plane which was what he wants. In the cargo hold, Kayo attacks the Hood and while they fight, they damage a fuel tank in the process. After the Hood departs in an escape pod, kayo returns to the cockpit and informs Scott and John that the plane is leaking fuel. John tells Kayo that the longest landing strip she could land Fireflash on is an abandoned spaceport in the Gobi Desert. After dropping down to subsonic speed, Scott performs a flyby to check there was no damage on the fuselage. As Fireflash approaches the runway, Kayo deploys the landing gear but one wheel lowers and the landing was aborted.
After Kayo tells Scott that when the plane lands without landing gear causing the leaking fuel to ignite, Virgil, Gordon and Alan arrive on Thunderbird 2. Alan and Gordon convert the two pods into Elevator Cars. When Fireflash lands on the Cars, Gordon worries that the plane is too heavy and it might crush them. Kayo takes off again and the exhaust from the plane’s engines causes the Elevator Cars to crash.
Kayo tries to crash Fireflash into the desert, intending that she might sacrifice herself. She tells the Tracy brothers that she appreciates them for coming to her rescue and she never started her life with them. Virgil brings Thunderbird 2 over Fireflash and fires the grappling cables around the plane, landing it safely. Kayo exits the plane just before the co-pilot and the passengers wake up. Scott thinks they did a great job and Kayo thinks she cannot fly commercial again.
- Kayo: Angel Coulby
- John Tracy: Thomas Brodie-Sangster
- Alan Tracy, Scott Tracy: Rasmus Hardiker
- Virgil Tracy, Gordon Tracy: David Menkin
- The Hood: Andres Williams
- Note: the following section is large. As such, it is hidden by default.
- Voice director: Dave Peacock
- Original dialogue record: Simon Capes, Soho Squares Studios
- Miniatures: WETA Workshop
- Design & miniature FX supervisor: Richard Taylor
- Lead model maker: Steven Saunders
- Workshop supervisor: Rob Gillies
- Production co-ordinator: Holly Beals
- Model makers: Sofia Pedersen, Mona Peters, David Duke, Joaquin Loyzaga, Laura Marie King, Abigail Smith, Masayuki Ohashi, Pietro Marson, Sourisak Chanpaseuth, Kim McAuslan
- Director of photography: Simon Godsiff
- 1st assistant director: Robin Wilson
- Production manager: Sadie Wilson
- Gaffer: Simon Oliver
- 1st assistant camera: Graham Smout
- Key grip: Byron Sparrow
- On set model technicians: Rob Chesney, Ben Fairless
- Lighting equipment: Portsmouth Lighting, NZFX SFX Equipment
- Catering: Deborah Logan
- Art director: Theo Baynton
- Designer, Thunderbird Shadow: Shoji Kawamori
- Lead concept artist: Christian Pearce
- Concept artists: Aaron Beck, Gus Hunter, Rebekah Tisch
- Head of design: Richard Athorne
- Design studio co-ordinators: Tasha Guillot, Catherine Mitchell
- Asset supervisor: Sven Trotter
- CG modellers: Ben Hutchinson, Thomas Oates, Ben Picking, Che Thorpe
- 3D story supervisor: Tim Gaul
- Lead 3D story artists: Karl Essex, Martin Haughey, Andrew McCully
- Matchmove: James Donald, Luke Swasbrook
- 3D story: Shinji Dawson, Nicholas Dodwell, Eduardo Gutierrez, Rhys Hanan, Jim Hatibarua, Nagaraju Kasama, Kai Ma, Yohann Misst, Ben van de Laar, Robin Wilson-Davey
- Production executives: Ivan C, Andy Tsao
- Head of production: Sareana Sun
- Line producer: Diana Chen
- Production team: Sean Li, Lara Lin, Tsung-Hsein Tsai, Bernie Huang, Pang Sy, Joseph Cheung, Yao-Cheng Wang, Heyifang, Tan Tao, Xu Ding, Shiwei Yang, Aimee Zhang
- Editor: Anthony Cox
- Assistant editors: Louise Pattinson, Adam Reynolds
- 3D artist: Rhys Clapcott
- Software engineer: Mike King
- Animation supervisor: Chad Moffitt
- CG supervisor: Andrew Harris, Park Road Post Production
- Data wranglers: Joyce Kamille Cristal, Wattana Moeung, Clare Brody
- Casting: Peacock Sound
- VFX line producer: Malcolm Angell
- Production co-ordinator: Sophie Gregory
- Production assistants: Brittany Connell, Jordan Harding
- Production secretary: Christine Healy
- Production runner: Nate Hinde
- Script co-ordinator: Patrick Rieger
- Legal and business affairs: Sally Perry, Sarah Cull
- Production accountants: Emily Stafford, Karen Kong
- Special advisor, International Rescue: David Tremont
- Branding and title design: ITV Creative
- Compositing: Milk VFX
- Online editor: Simon Brook
- Colourist: Paul Staples
- Picture post production: Encore London
- Sound effects editor: Adam Armitage
- Foley engineer: Keith Partridge
- Mix technician: Kiran Marshall
- Audio post production: Jules Zabbar
- Music composed by: Ben Foster, Nick Foster
- Original theme: Barry Gray
- Sound designer & re-recording mixer: Nigel Heath
- Audio post-production: Hackenbacker
- Producers: Sharon Lark, Stuart McAra
- Line & consulting animation producer: Teresa Reed
- Supervising producer: John Sanders
- CITV commissioning editor: Jamila Metran
- Executive producers: Estelle Hughes, Giles Ridge, Andrew Smith, Richard Taylor
- Based on the original series by: Gerry & Sylvia Anderson
- This episode was confirmed by Rob Hoegee shortly before the series began.
- Unfortunately, they do not dump marbles on the runway to save Fireflash this time around.
- During Fireflash's takeoff in the opening scene, you can hear the sound of the original Fireflash.
- Along with the basic plot of Trapped in the Sky (The Hood sabotaging the Fireflash Airliner and the Elevator Control Cars helping it land), certain further story elements are a homage to Alias Mr. Hackenbacker (an airliner designed by Brains is taken over by a hijacker).
- During the landing attempt, a remix of the music used for this sequence in the original episode can briefly be heard.
- This episode sees the return of Elevator Cars, first (and last) seen in the story's classic counterpart.
- Fireflash is stated to be capable of flying at Mach 5 at 75,000 feet. Therefore, the plane is downgraded compared to the Fireflash in the original series.
- Kayo's line "...could turn Fireflash into Fireball." is a reference to 'Fireball XL5'.
- This episode marks the first time a pod vehicle has been destroyed, with the Elevator Cars having been destroyed in a failed landing attempt. This was followed by a Pod Explorer driven by Scott in Recharge, and a space variation of the explorer in Colony.
- Just like the episode it pays homage to, Fireflash is the only one in the series to feature a sound effect in the opening credits teaser - just as with Kyrano's scream in the original, Fireflash zooming down the runway can be heard here.
- There are a few shots where Kayo is trying to land the Fireflash and the port wing landing gear is up.
- The sounds of International Rescue celebrating Fireflash's final successful landing are a repeat of their reactions to the first landing attempt; Kayo's voice can be heard over the radio while she herself is on screen in person.
- Dutch: Fireflash
- French: L'éclair de feu
- Spanish: Cometa
- Japanese: 消えたファイアーフラッシュ (Missing Fireflash)