The other crew member reports that something seems to be going wrong with the ship's reactor, as it is entering the "danger" state. The crew then see that there is a lot of mist in front of them, which is strange as none of the weather reports they've seen mentioned anything about mist.
The ship enters this mist anyway, but minutes later, it explodes! Not much is left of Ocean Pioneer I.
Months later, Ocean Pioneer II is ready to go. Lady Penelope Creighton-Ward is there to see the ship off, and after making a speech, she christens the boat in the traditional bottle smashing manner. The ship is released and enters the waters. The event is being filmed by TV crews, and on Tracy Island, the family watch a report. The reporter mentions that whilst everyone here is cheering for this new boat, some will be thinking of the first Ocean Pioneer, which disappeared so tragically 6 months ago. Jeff Tracy says they just need to wait until Penelope reports in, and wonders if she will find anything interesting.Penelope does find something interesting: a very drunk Parker. She asks him where he got that vintage 1998 champagne from, and he admits he switched it with the bottle she used to christen the ship - the bottle she hit the ship with just had tonic water in it. Penelope says she will discuss this with him later, but goes to contact Jeff. She says she got to take a look around the ship earlier but could not find anything strange, such as sabotaged equipment. She believes there is nothing wrong with the Ocean Pioneer II. Jeff thanks her for checking it out.
Despite her saying it looks fine, Jeff is still concerned about the ship. The first one blew up for no reason, and he thinks something could happen to the second one. John Tracy then contacts Tracy Island, but what he tells them has nothing to do with the Ocean Pioneer II -instead, a typhoon has hit an island somewhere in the Pacific, and damaged a hospital. The foundations are crumbling, and the patients are in danger. Scott Tracy takes off in Thunderbird 1 immediately.
Scott approaches the danger zone and has found out more info from John. He needs Thunderbird 2 sent out with Pod 3, and Virgil Tracy and Gordon Tracy are soon in the air. Scott makes another transmission, but his signal breaks up. Virgil then calls in, but his signal also comes through funny - the picture is messy and there is no sound. Brains says they have also lost contact with Thunderbird 5. Jeff is concerned as without communications they could be in a lot of trouble. As Alan Tracy was due to relieve John in 6 hours, he asks him to go to Thunderbird 5 now and take Brains with him. Minutes later Thunderbird 3 blasts off.Thunderbird 3 docks with Thunderbird 5 and Brains listens to the interference. He collects a tape of it and then is ready to return to Earth. Alan thinks it was a long way for him to come just to get that, but Brains says he needs it. John gets ready to go, but Alan tells him to remember this - he owes him 6 hours! John laughs it off and bids him farewell for now.
Thunderbird 3 leaves Thunderbird 5 and heads back to Earth. Meanwhile, Jeff is telling Kyrano about how much they rely on communication, but at the moment, he believes that only short-range communication may be possible - such as between Thunderbird 1 and Thunderbird 2. They then hear a noise and realise that Thunderbird 1 is approaching Tracy Island.
Scott lands and explains that the rescue has gone fine - other than them getting a bit muddy. Virgil and Gordon are on the way back, but Scott says that he was only able to communicate with them when they were at short-range. As he goes off to get cleaned up, Tin-Tin Kyrano says a program about the Ocean Pioneer II is coming on. Jeff says he'll take a look at it before Virgil and Gordon come back. Later on both Thunderbirds 2 and 3 return, and Brains get to work on that interference tape he had.
Jeff watches the report, which shows the boat sailing with no problems at all. It mentions how the ship has only 3 crew members and that it is powered by liquid alsterene. On the ship, the crew report in that they have had no problems so far, and continue on the same course the original Ocean Pioneer was on.Brains then contacts Jeff and tells him he has found out what is wrong, although it is a bit complicated. Jeff heads down to the lab, where Brains is running an experiment. He gets Tin-Tin to put some chemicals into a container, and then she starts running the tape he got of the interference. He asks her to stop it and then has her turn the microphone on inside the container with the chemicals. The experiment shows that when in close proximity with a high density fuel and a low density substance known as OD-60, high impendence waves are produced. These are what have been effecting their communications at great distance. Jeff says that is the cause, but they need a cure. Brains says not so fast, and shows what happens when the two substances are moved closer towards each other: the substances explode. Scott has been trying to find a fix on the source of the problem, but the location he has doesn't make any sense to him, as it is in the middle of the Mediterranean, miles away from the gulf stream and miles away from the nearest land.
Jeff asks if this OD-60 is only found in the one place he mentioned, and Brains says he thinks it is. Tin-Tin says Penelope could help them -she is going to be a judge for a dog show ran by Allpets, the company who use OD-60. She should be able to find something out. Jeff tells Tin-Tin to contact Penelope. He has a hunch that if Ocean Pioneer II remains on the same course, it will meet the same fate as Ocean Pioneer I, as it is carrying several tons of liquid alsterene.Penelope goes to the Allpets office, and meets the boss of the company, Sir Arthur. She claims she is writing a book about dogs and mentions feeding, as she thinks her readers will want to know about OD-60. Arthur says he knows he can trust her as he wouldn't want everyone knowing where their sources are, and he reveals a map behind a poster. The map shows the locations of OD-60, which is around the coast of Florida, up from the gulf stream. Penelope asks if this is the main source, then are there other sources? Arthur reveals that the main source is quite a distance from his production facilities, and the shipping costs were crippling his company. So he came up with an idea -he had 50,000 tones of OD-60 collected, and then dumped in the sea in the Mediterranean in the hope it would flourish, plus they can access it much easier. Penelope thanks him and promises not to tell anyone. She and Parker head out, as Penelope says their worst fears are confirmed. She needs to contact Jeff as Ocean Pioneer II is heading straight for trouble.
Scott tries to contact Ocean Pioneer II but cannot get through to it. As the crew wouldn't be able to call them if it wanted to, Scott says they need to move. He blasts off in Thunderbird 1, and Thunderbird 2 is launched not long after. Meanwhile, on Ocean Pioneer II, the crew realise that they can no longer seem to communicate with their base. And then, they see that there is something wrong with the ship's reactor. They try to get it under control, but nothing they do works and the reactor enters the "danger" state. The ship speeds up to 60 knots. The Captain then notices that the weather is now even getting worse.Not far away, there is a lot of mist. The ship is now going at over 85 knots, and heads straight into the mist. With the reactor entering the critical phase, the Captain knows there could be a radiation hazard and has the windows locked down. However, with the ship's reactor in a critical state, it overloads. The ship suddenly loses all power. It slows down immediately, but now the crew are in trouble as the air con has broken down and they are finding it difficult to breathe. The Captain tries to contact International Rescue, unaware that they are already on their way - Scott is above the ship in Thunderbird 1. He tells Virgil that the ship is drifting off course, straight towards the danger zone, and he is going to try and land on the deck.
Scott lands and takes a look around outside, noticing that the mist is getting very thick. He hopes Virgil will be able to find the ship. Up above, Virgil and John arrive in Thunderbird 2 and see the thick mist. Scott attempts to communicate with the crew but gets no response as they have passed out. He then hears Thunderbird 2's engines and has to guide Virgil towards where the ship is. Virgil stops above it, as John heads down to join Scott. As John gets onto the deck, Virgil moves Thunderbird 2 away.Scott starts to use a laser to burn through the door to the bridge. He burns through and knocks it down, and find the crew inside. As they go in, John notices how the water is bubbling and Scott says they must be directly over the OD60.
John contacts Virgil and tells him to move back in and fast, as they may not be around if he takes too long. Scott awakes the crew as Virgil appears over the Ocean Pioneer II. The crew is up and about to be taken off the ship, when the Captain starts to thank Scott. However Scott says there is no time as the ship is about to explode. Virgil lowers down the ladder for the crew and John to climb up, and then moves away. Scott quickly gets into Thunderbird 1 and takes off, as the ship starts to explode.The Thunderbirds are clear as the ship is destroyed. Later on, at Tracy Island, Scott and John talk about the rescue. John thinks that they should have tried to save the ship, as it was carrying a lot of valuable material. Scott says sure, but they had no idea if they would have made it out in time if they had tried to tow the ship. John says that is all part of the game. Jeff tells them to hold on for a second and asks how many rescues John has been on. John says he has been out on a dozen or so. Jeff then asks Scott, who tells him he has been out on all of them. Jeff says despite this they are still arguing. They say they weren't arguing, just discussing what happened. Jeff says that for many years man has tried to perfect the material things in this world, and has done well. If a building falls down he can soon build it up again. But with life, things are different, and this is why the objective of International Rescue will never change. Their job is to save lives that are in danger. Scott and John say they understand.