A man known as the Hood uses his special powers to contact his brother, Kyrano. Kyrano works for the Tracy family, who have their own island. The Hood also knows that the Tracy family are about to start something called International Rescue, and believes he could become the wealthiest man in the world if he could get their secrets. He mentally tortures Kyrano and finds out that International Rescue are ready to start operating. The Hood heads to London airport, where a new plane called Fireflash is about to begin its maiden flight. Onboard the Fireflash is Tin-Tin, Kyrano's daughter.

Fireflash takes off, with nobody knowing that the Hood has installed a bomb in its landing gear. He contacts the control tower and reveals what he's done. The staff there have the plane return to London, where they photograph it with an X-ray camera. They find that there really is a bomb onboard, and wonder what they can do -the Fireflash is atomic-powered, but its anti-radiation shielding will only hold out for around 2 more hours before needing servicing. If this doesn't happen, the crew and passengers will be exposed. If the plane attempts to land normally, the bomb will most likely go off, and the explosion will spread radioactive material everywhere. From the space station Thunderbird 5, John Tracy contacts Tracy Island, and informs Jeff what's going on with the Fireflash.

Jeff sends Scott out in Thunderbird 1, which takes off and heads to London airport. Virgil boards Thunderbird 2, and has his aircraft select pod 3. He then takes off and heads to London. Meanwhile, Bob Meddings has come up with a plan to try and get himself into the Fireflash. He has another aircraft usually used for target carrying purposes winch him over to the Fireflash.

He is able to board the Fireflash, but cannot get to the bomb from where he is. He attempts to move around, but ends up falling out of the plane. He survives thanks to his parachute, just as Thunderbird 1 arrives at the airport. Scott lands and asks for his aircraft to be guarded, with no photographs of it to be taken. He has some equipment moved up to the control tower, and finds out that Fireflash can only stay up in the air for around another 30 minutes. With Thunderbird 2 still around 20 minutes away, it'll give them just 10 minutes to make the rescue attempt.

The Hood, now disguised as a policeman, is able to enter Thunderbird 1 and start taking pictures of it. This sets off an alarm which Scott notices, but the Hood is able to drive away before anyone can stop him. Virgil arrives in Thunderbird 2, and drives out in an elevator car. This is followed by two other cars, which are remote controlled. Scott contacts London agent Lady Penelope, and asks her to deal with the Hood. She and her butler Parker head out in their car, FAB 1.

The rescue attempt begins, with the plan being for the Fireflash to land on the three elevator cars. The initial attempt has to be aborted at the last moment, when one of the elevator cars goes haywire and crashes into another plane. A fourth elevator car is used, and the rescue attempt begins again. This time, the Fireflash lands on the cars, and uses its reverse thrust to slow down. Virgil applies the brakes, but they're about to run out of runway. As some of the elevator car's tires start exploding. Virgil moves his car out of the way and then uses it to move the Fireflash aside. His car then crashes, but the Fireflash comes to a stop without the bomb exploding.

Penelope and Parker track down the Hood, and use FAB 1's grill gun to destroy his car. He crashes through a barrier and down a bank, but he survives. As Penelope and Parker return home, the Hood sees that his pictures have been ruined. He vows that someone will pay for this, and that International Rescue haven't heard the last of him.

At Tracy Island, a doctor has checked over the Kyrano, and given him the all clear. He sees a newspaper that Jeff is holding, which has a front page story about International Rescue. The doctor wishes he could shake them by the hand, so Jeff gives him a handshake. As the doctor leaves, Jeff tells his family that the handshake was for all of them -he thinks they're in business!

Notes

-This episode's opening preview features some voices and sound effects as it plays. Future episodes don't have these things.

-The opening preview also features a couple of oddities, showing different shots to what's actually used in the episode itself:

Preview	Episode

The shot of the Fireflash nosecone has more sparks in the preview, but the runway is moving a lot slower than it is in the actual episode.

-Many versions of this episode lack the on-screen title that all future episodes will feature.

-The name "The Hood" is never spoken in any episode of the series itself.

-Alan Tracy is normally voiced by Matt Zimmerman, but for this episode, his single line was voiced by Ray Barrett. Ray voices several other characters, including John and the Hood.

-Robert Meddings is named after two people -Robert Bell, who was the art director of AP Films, and Derek Meddings, the special effects director for the series.

-Originally, each episode of Thunderbirds was meant to fill a 30 minute time slot -meaning around 22-23 minutes per episode. However, upon viewing the completed episode, ITC director Lew Grade said it was good enough to be a feature film, and demanded that each episode be an hour long. The production team went back to work on episodes they'd been working on to include more scenes.

-This episode is the longest episode in the series -most are roughly 47-48 minutes long including the opening and closing credits, but this one has a run time of 51 minutes.

-The scene where one of the remote elevator cars crashes was not in any script -Derek Meddings requested it to be added in after he and his team made a mistake with one of the models, making it veer off the set suddenly.

-The music featured in the credits for this episode is the music used for Thunderbird 1's launch. Originally, another song called "Flying High", sung by Gary Miller, was going to be used, but this was dropped. Future episodes use an alternate rendition of the opening theme.

-The credits feature several pictures of various International Rescue machines. The only non-International Rescue related vehicle shown is the Fireflash.

Errors

-When the Hood starts his call to the control tower, his truck is nowhere to be seen. When the call ends, his truck is suddenly there.
-When the target gets blown up, a piece of it can be seen rebounding off the sky backdrop.
-Did it not occur to the Fireflash pilots to close the inspection hatch once Meddings got inside?
-There are a few shots throughout the episode where Thunderbird 1 is missing the "TB1" text near the front nose cone and lower back engine. As some of these shots are used as stock footage in later episodes, I'm only going to mention this here.
-When the Hood is looking around Thunderbird 1, the "AIRPORT POLICE" text on his hat is missing.
-Another error during the above scene is that Thunderbird 1's cockpit appears to be in its vertical position, instead of horizontal.
-There are also a few shots, most famously this one, where the white "T" is painted on the red nosecone of Thunderbird 1. This error is also featured in the intro.
-The voices during this shot are very noticeably out of sync for most of it.
-Another famous error happens near the end -Jeff puts operation cover up into place, but when the doctor enters the room, the pictures of the Tracy boys have suddenly changed back to them in their uniforms.