At the mobile base control of the Crablogger, Simms says the Crablogger crew are late. Jansen tells Simms to cut out the time checks, as McColl knows what he's doing. Simms thinks he doesn't understand the importance of this operation, but Jansen claims he does, and is just as keen to get started as he is.
Franklin reports he's all fixed up, and guesses this must be the biggest thing anyone has programmed a tape for. They see on a map the progress of the Crablogger, which is heading towards the base camp. Jansen contacts the Crablogger crew and welcomes them to the base. The base control crew then see the gigantic Crablogger vehicle moving towards them.
The Crablogger is operated by just two people: McColl and Peterson. McColl tells Peterson not to get the Crablogger too close to base control, as it might make them worry. Peterson supposes they've never seen a machine quite like this, and he has it stop next to base control. McColl says they can make a fresh start in the morning, so Jansen tells him that he'll show them the sights tonight. Everyone other than Simms is going, as he wants to fix up a couple of things for tomorrow's start.
Jansen takes everyone to a restaurant. He asks if this is their first trip to the tropics. Peterson says it is, and that they've been working pretty closely with Jim Lucas from the early design days. McColl says that naturally Lucas wanted them to come with the Crablogger on its first contract. Jansen is glad they have experts here. Sanchos, who owns the place, then comes over and sees that Mr. Jansen has brought some new clients. McColl asks if they can see the menu, but Sanchos says they don't have one. But he can prepare them something very special. Almost everyone decides to order a special, apart from Jansen who decides to have his usual steak.
Sanchos goes to his rat infested kitchen and tells his cook Maria about Jansen's new colleagues. He wants her to hurry up, but she says everything in this place is "hurry". She says they'll have to wait. Back at the table, Jansen draws some plans on a napkin and talks about tomorrow's plans. Simms is going to have a fleet of transporters and tankers to feed the Superon liquid gas tanks. They are programmed to be produce 60 barrels of pure wood pulp every 30 minutes.
Franklin says each quarter hour a transporter will receive 30 barrels of pulp, and every 3 hours a tanker will link up with the Superon tanks. McColl says he can't wait to get started tomorrow, whilst Peterson wishes Jim Lucas was here, so he could see the Crablogger show its muscles. In the kitchen, Maria says the food is ready. Sanchos wheels it out and says here they are. Jansen says this is their chance to get all the energy they'll need for tomorrow.
Sanchos presents McColl, Peterson and Franklin with their specials. Later on, everyone returns to the base control site. Jansen tells Simms to get this operation underway. Simms starts entering Franklin's data into a computer, to set up the path that the Crablogger will be taking.
Jansen looks at a map and says he wishes Franklin was here for the start of the clearing operation. Simms says he's worried about that guy, as he sure is sick. Jansen says as soon as the operation is underway, he'll radio for a doctor to take a look at him. Meanwhile, McColl and Peterson are taken up to the Crablogger via an elevator platform. They enter the Crablogger via another elevator on its roof.
McColl locks the entrance hatch and then tells Peterson to put the radiation shields on place. A shield drops down over the windows and Peterson then turns the screens on. McColl says here they go, as the Crablogger begins to move. McColl and Peterson are able to see things outside via a screen, as the clearance begins.
The Crablogger rips out any trees in its way and feeds them into the spiked rollers at the front of the vehicle. Jansen says Operation Crablogger is underway, and it looks like a success. He wishes Lucas was here to see it. Inside the Crablogger, McColl says it's getting hot in here. He asks if the fans are on, but Peterson says they're on alright. McColl then reports to base control that they're nearly ready to release the first cargo, so they need to get the first transporter to stand by.
McColl tells Peterson that the transporter is on its way, so he needs to switch to remote. But Peterson then collapses. Meanwhile, the transporter arrives behind the Crablogger. The Crablogger opens up, and the wood pulp begins to come out of it, landing in the back of the transporter truck.
McColl reports that Peterson has passed out, and he's not feeling to good himself. Jansen tells him to deliver the first load, then take the Crablogger off remote and close down the reactor. McColl says they can't do that, and assures that things will be alright. He says he can handle the Crablogger himself, but Jansen tells him he's calling the operation off for today. However McColl then also passes out.
The control site look at the map and see that the Crablogger is already going off the programmed route. Jansen says they can't stop it, McColl can't have gotten to the remote switch in time. Simms says there is a village right in the path of the Crablogger. The Crablogger continues to move through the jungle, obliterating anything that gets in the way. Jansen says they'll have to keep feeding the Crablogger with Superon and keep the transporters unloading it. If that processing machine gets jammed, the whole thing could explode and raze everything to the ground within a 50 mile radius. Simms thinks what happened to McColl and Peterson must be the same thing that happened to Franklin -it had to have been Sanchos' special.
Jansen says there is only one outfit that could handle this situation. He makes a call to International Rescue and says it's an emergency. In Thunderbird 5, John answers the call and finds out the details. Jansen explains that the village has been warned, and they've sent one of the transporters to assist in evacuating it. If the Crablogger gets there, the processing plant will get jammed for sure, but anything could happen. Whilst it may bypass the village, one thing is for sure: it'll hit the San Martino Dam. John contacts Tracy Island and explains the situation.
Jeff tells Scott he'd better get out there straight away. Scott heads off to Thunderbird 1 and takes off. Jeff asks Brains if he has any idea on how they can cope with this. Brains says that Jim Lucas is their man, as he built the Crablogger for Robotics International in England, and should be able to answer all of Scott's danger zone queries. Jeff thinks if they wait for International Rescue to get there, it may be too late for him to be able to help them. Virgil points out it'd also mean revealing their identity if they contacted him directly. Jeff says he has a better idea.
Penelope is about to have dinner, but then she gets a call from Jeff which she takes on her candle radio. She asks him if it's business or pleasure, so he tells her that it's always a pleasure to do business with her. He says he wants her to contact Jim Lucas of Robotics International, who is the company's chief design man. They need to know the shut down procedure of the Crablogger, as it's a matter of life and death. He knows it'll be late evening where Penelope is, so Penelope says the guy won't be working now. Jeff says that makes things a bit difficult, but they must contact him, as people's lives are in danger. Penelope says to leave it to her.
Scott says he's proceeding to the danger zone and asks if there are any developments. Jeff says he's contacted Penelope and asked her to get the shut down procedure for the reactor in the Crablogger. Meanwhile, Virgil and Brains board Thunderbird 2. Brains says he just hopes that Penelope can find Jim Lucas. Thunderbird 2 then rolls out onto the runway and takes off.
Tin-Tin says another rescue operation is underway. Jeff just hopes they can pull this one off, as that machine has just got to be stopped. Meanwhile, the Crablogger continues towards the village. In the village, police officer Gutierrez tells Jansen that the last truck has just left the village. Jansen tells him to clear out now, as that machine will be on top of him at any moment. Gutierrez says he can hear it.
The Crablogger smashes through a wall. Jansen tells Gutierrez to get the heck out of there, as if the processing unit gets jammed with bricks and mortar, the bang will be heard a hundred miles away. As the Crablogger continues to drive through the village, Gutierrez says he'll see what he can do at the dam, and heads there via his police car.
The Crablogger smashes through another wall, but keeps on going. In Thunderbird 2, Virgil tells Scott they're about 18 minutes behind him. Scott says that means they have about 45 minutes before the Crablogger reaches the dam. Scott arrives at base control and lands Thunderbird 1.
Scott reports that he's now at the danger zone, and Virgil will be arriving in 15 minutes -giving them just 42 minutes to cut into the Crablogger and shut down the reactor. He thinks they will be able to get into the Crablogger ok, but they must have the shutdown procedure for the reactor as soon as they do. In England, Penelope has gone to Robotics International, but the security guard won't give away the details of Jim Lucas -he can't reveal such information without written permission. Penelope says it's terribly important, but he says she won't say why. She says she can't explain, but then notices the personnel files next to her. Since the guard won't change his mind, she says she can't wait any longer.
She signals Parker, who uses some kind of hypnotic ray on the guard. The guard wonders what's going on, whilst Penelope opens the drawer and takes a look at the relevant file. She soon finds where Jim Lucas with, and apologizes to the guard for inflicting this on him.
She says that she has to find Mr. Lucas tonight, but assures the guard he'll suffer no after effects from this beam. As she leaves, the guard collapses onto the alarm button. Penelope and Parker get into FAB 1 and quickly leave. Parker trusts she got the information she requires. Penelope tells him his aiming, as usual, was impeccable. Parker asks where they are going now, so Penelope tells him the address.
Thunderbird 2 lands at the danger zone. It raises up and the pod door opens, revealing the Mobile Crane. Scott, Virgil and Brains drive out of the pod in it, as Scott contacts the Crablogger base and asks how long before the Crablogger reaches the dam. Jansen tells him about 34 minutes, so Scott says they'll be hearing from them.
Parker brings FAB 1 to a stop, as he's seen an accident up ahead. They see a car flipped over and the driver has been ejected from his vehicle. Whilst they know they haven't got much time to deal with this right now, they decide to help him. Parker is sent to get the first aid kit out of FAB 1, whilst Penelope says she'll call for an ambulance.
The Mobile Crane drives up to the side of the Crablogger. Virgil and Brains stand on the crane's platform, so Scott has it move upwards. The crane's platform is moved into position by Scott, who gets it close enough to the Crablogger for Virgil and Brains to jump onto it. Virgil reports that they are aboard, but Brains says they're going to need Penelope's information about the reactor pretty soon.
The injured driver has been tended to. Penelope has called the police and explains where the driver is. She thinks he may have a broken leg, but then says she can hear the ambulance. She explains to the police that she really must dash, as she has a terribly important appointment to keep. She ends the call and tells Parker to drive.
Jansen tells Scott that they've got about 13 minutes left, and unless the reactor in that machine is shut down before it reaches the dam... he hates to think what would happen. Scott asks how things at the dam are. Jansen says the site is being evacuated now, he's waiting for final confirmation of clearance. At the dam, some vehicles move away. Gutierrez says the last of the transporters have left. Manuel asks base control how much time is left.
Jansen tells him he has less that 13 minutes until the Crablogger gets to the site. Manuel claims he can't leave yet, he's got to get his papers together. Jansen tells him when that Crablogger falls into the dam, as it's going to do in about 10 minutes, the reactor will explode and tear the wall of the dam apart, releasing so much water into the valleys that not one village is going to be left standing. Manuel moans that there was only 2 more weeks work left to complete the dam, but now, they're evacuating. On the Crablogger, Virgil uses a laser beam to cut into the control cabin.
Penelope and Parker arrive at the home of Jim Lucas, but they find that there isn't a single window or door unlocked. Penelope says that there's only one thing they can do, seeing as men's lives depend on it. Parker understands, and asks her if he can loan one of her hairpins. Back at the Crablogger, Virgil finishes using the laser beam. He and Brains enter the control cabin and tells Scott the sooner they get McColl and Peterson out of here, the better. Scott asks about the reactor, but Brains says he doesn't dare touch the controls without knowing the closedown sequence. Scott says to get the two men out first, but they'll have to wait for Penelope -she's the only one who can save the situation now.
Jim Lucas wakes up and realizes that someone has a gun pointed at his head. Penelope tells him not to move, so he asks who she is and what she wants. Penelope tells him to keep quite still and no harm will come to him. She also tells him to be quiet, they don't want to disturb his wife. She says that in a few seconds she will ask him to repeat the closedown sequence for the reactor of the Crablogger, the machine he designed.
She places a recorder down and tells him to go ahead. He wishes he knew what this was all about, but Penelope says there is no time to explain, as men's lives depend on her getting this information. Lucas starts going through the sequence. At Tracy Island, Jeff wonders if the boys have gotten the men out of the Crablogger yet. John then contacts them, confirming that Virgil and Brains have gotten the crew out and base control are having them shipped out to hospital. He's now waiting for Penelope's instructions.
Lucas finishes saying what the closedown sequence is, but also mentions that the unit incorporates a time lag of about three minutes, after which the Crablogger should stop. Penelope stops recording and tells him he's been most cooperative. She throws Parker the recording and then tells Lucas she's going to leave him. For reasons too complicated to explain, she will also send him back to sleep.
She shoots him with a tranquilizer. He says he wishes he knew what this was all about, as he hoped to get to know her better too -she certainly has a lovely voice. As he goes to sleep, Parker plays the recording back to John. John then transmits it to Brains and Virgil, who use it to shut down the Crablogger's reactor. But when Virgil hears the bit about the 3 minute time lag, he tells Brains they'll never make it in time!
Brains says they might as well take a look outside. He has the radiation shields raised, as Virgil tells Scott they've closed down the reactor and are now waiting for the time lag to run out. Scott asks what are the chances, so Brains says they're heading for a ledge. Scott says they've got to get those Superon tanks empty, as if the Crablogger falls into that basin, even with the reactor stopped, the tanks will go up and bust the walls of the dam. Scott says he's coming in now, but Jansen and Simms thinks there isn't enough time. Scott says they aren't just going to sit back and do nothing.
The Crablogger is still moving forwards, causing the ground under it to break up. Scott drives one of the Superon tankers towards the Crablogger and tells Virgil and Brains to get onto the roof of the processing plant and be ready to hook up the pipelines. Jansen explains to Scott where the fuel release valves are on the master tank, and how the tanks on the Crablogger work.
Jansen then notices on the map that the Crablogger's signal is getting fainter. He says the Crablogger's reactor is closing down, but Simms says it's still too near the end of that ledge. The Crablogger is still going, as the ground beneath it still crumbling away. But then the Crablogger comes to a complete stop, just as Scott arrives. He activates the tanker's pipelines, which extend out to where Virgil and Brains are.
They hook the pipes into the Crablogger's main tank, so Scott starts up the pumps. The Crablogger's main fuel tank slowly starts to drain. But the ground beneath the Crablogger is still falling apart, and the entire machine is about to tip over.
The fuel tank finishes draining, just as half of the Crablogger tips over the ledge. Virgil tells Brains to jump, as the two of them use their rocket packs to leave the Crablogger.
The Crablogger moves over the ledge and falls down, where it lands on a few small buildings and explodes. Brains says that was quite a bang, but Scott says it could have been a much bigger one. Virgil wonders what Jim Lucas will say when he hears about his Crablogger. Soon, news of the Crablogger's destruction is on the front pages.
Lucas reads the story and says that it explains it. He thought it was a dream, but that girl in the bedroom... he didn't dream it, she really was here! His wife asks him what he's talking about, but he says never mind, he'll tell her about it later. He guesses it's back to the drawing board with the Crablogger, as they don't want to have to call out International Rescue again. His wife asks him again about this girl in the bedroom...