The nuclear-powered hypersonic jetliner Fireflash has been sabotaged by the villainous Hood. Trapped aboard are hundreds of passengers - including Tin-Tin Kyrano, a member of a new organisation, International Rescue. With just hours before their radiation shields fail and the passengers and crew die of radiation poisoning, the fledgling organisation must race to London Airport in their Thunderbirds and find some way of bringing Fireflash down without detonating the bomb.
Unbeknownst to International Rescue, the Hood planted the bomb with the intention of drawing them out, so that he could take pictures of the Thunderbird craft. While he succeeds in taking the pictures, International Rescue's London agent, Lady Penelope Creighton-Ward and her chauffeur Parker are able to intercept and destroy his film and his car with their heavily-armed and bright pink Rolls-Royce.
- Atom Punk: The dangers of nuclear power on Fireflash are recognised, but everyone seems to consider it an acceptable risk under normal circumstances.
- Battle Butler: Parker guns down the Hood whilst driving FAB 1.
- Cool Car: FAB 1 makes it debut here, where it is firmly established as such.
- Early Installment Weirdness: There's plenty of it, though not necessarily to the episode's detriment:
- The arrangement to the theme song is slightly different.
- This is the only episode where audio accompanies the preview clips.
- The Hood's clothes are different.
- Alan's one line is spoken by Ray Barrett as Matt Zimmerman had yet to be cast.
- This is one of the episodes that was stretched from 20 to 40 minutes. With the botched initial rescue attempts and the abundance of stock footage, it's fairly noticable.
- Glowing Eyes of Doom: The Hood's psionic powers are introduced through these.
- Hollywood Skydiving: When Lieutenant Meddings falls out of the Fireflash at less than 6,000 feet, he has time to activate his reserve parachute and land safely.
- Incredibly Obvious Bomb: The bomb was meant to be out of sight, buried in the wing, but still sufficiently obvious to be instantly detectable by the control tower's x-ray camera.
- Million to One Chance: The odds everyone describes an officer's daring plan to board the Fireflash in midair to remove the bomb. As such, no one is particularly confident in it, and it doesn't work.
- Mission Control: Scott takes on this role upon arrival at London Tower, relaying information to Virgil on the runway.
- The Mole: The first instance of the unwilling Kyrano filling this position.
- Stuff Blowing Up: Elevator Car No. 3 spirals out of control and crashes into a parked airliner which instantly bursts into flames.
- Theme Tune Cameo: Virgil ends the episode with an adaptation of the theme on his piano.
- X-Ray Vision: London Tower has a huge x-ray camera, apparently for confirming bomb threats. It's sufficiently advanced to get a nice, big, high-resolution shot, even though Fireflash is supposedly travelling at hundreds of miles per hour.