Alan and Grandma Tracy have been left on a bridge, which has a bomb on it with a two hour time limit. And worse, there's also a ultrasonic wave generator next to them, which will cause the bomb to detonate early should they disturb its energy waves. Alan is able to contact International Rescue, so Jeff sends Scott, Virgil and Brains out in Thunderbirds 1 and 2 immediately. The heat puts Alan in considerable danger, as he's been left standing there. Jeff tells him to go through what happened, and how they ended up on that bridge. Alan says it all began when he was dropped off in Thunderbird 2. Alan rolls out in a car designed by Brains, called the BR2. Allowed some leave from his International Rescue duties, Alan goes to compete in a race being held at Parola Sands.

Alan meets up with his old mechanic friend Kenny, but they then see previous champion Gomez and his buddy Johnny. After Alan and Kenny leave, Gomez and Johnny aren't happy that Alan is competing, as they are worried they won't win and won't get the prize money. The next day the race is on, and it comes down to a battle between Alan and Gomez. Alan eventually wins, causing Gomez and Johnny to seek revenge. As Alan calls Grandma to let her know he's on the way, Gomez and Johnny attempt to use a car stacker to push a car onto the telecall booth Alan is in, but Alan ends the call just in time and escapes with his life.

Alan picks Grandma up, but as they leave they are flagged down by Gomez and Johnny. They are taken to the bridge, and after Alan refuses to give them any details about his car, they decide to steal it. They have Alan and Grandma wait on the bridge, and explain what they've done with the bomb and the generator. They then flee the scene in the BR2, but the Thunderbirds arrive. Brains rides out in the neutralizer tractor, and uses it to neutralize the generator, making it useless.

Virgil then goes to the bridge driving the jet-air transporter. Alan falls off the bridge, but is saved by Virgil. Virgil then gets Grandma off the bridge safely, and the group then quickly get off the bridge. The bomb then explodes, causing the bridge to be destroyed. Meanwhile, Scott goes after Gomez and Johnny in Thunderbird 1, and shoots near their stolen car to try and make them stop.

Johnny tries to take control of the car, but his actions lead to Gomez losing control. The car smashes through a barrier and tumbles down a cliff. Later on, Virgil paints Alan's picture, although Alan is not happy having to stand still again. He's even less happy when he sees what Virgil has painted -his technique is about 100 years out of date! Virgil and Scott laugh it up, but Alan outsmarts them by using Jeff's desk controls to make the floor they're on move down, making the two of them drop. Alan asks Tin-Tin about the painting. She tells him never mind, as who needs a painting? Especially when she has the real thing.

Notes

-This episode must be set before the events of any that had Grandma Tracy in them.

-It's not known as to exactly what was added to extend this episode's length. My guess is that the strange sequence where the camera zooms in on a painting of cars multiple times was added. Perhaps the car stacking was added too, since it gets shown twice and goes on for a while.

-This is one of the only episodes where Thunderbird 2 is seen using pod 1. Pod 1 won't be used again until Security Hazard.

Errors

-When Jeff is first seen, he's sat behind his desk. We then see Alan again, and then a few seconds later we go back to Jeff. Only Jeff is suddenly sat on the front of his desk, the magazines on the desk are different and the books in the bookcase have been changed.
-When Thunderbird 2 raises up to reveal the pod, only the front part of Thunderbird 2 appears to have been built for this particular model of it -if you look towards the right you can tell the rest of it is missing! This happens both times the pod is revealed.
-When the BR2 is driving out the pod, it appears to be Virgil who's driving it instead of Alan -the figure in the driving seat is wearing an International Rescue uniform.
-Thunderbird 2 seemingly lands in a different place than it takes off from.
-For the smaller model shots, Gomez's car has a number 7 on the door. But for the puppet sized model, it has a number 7 behind where Gomez is sitting.
-When Alan contacts Grandma, during the close up shot of his hand pressing the buttons, the phone's controls have the letters on the left, and the numbers on the right. The controls have been switched during this shot.
-During this shot, Alan is on the right side of the car, whilst Grandma is on the left. They should be the other way around.