The World Navy are testing gyropedoes in the Atlantic Ocean near the drilling rig, when one of the gyropedoes - fired from the atom sub Reaper - ignites a gas field beneath the sea bed. The gas eventually breaks through, shooting columns of flames above sea level and high into the air.
Feeling themselves in danger, Frank and Dick go down in a diving bell to check the damage, after one of the drilling rig's legs is fractured.
Another explosion causes the rig to slip further and the diving bell crashes to the sea bed.
Scott launches Thunderbird 1 and 2, and Alan, Virgil and Gordon fly to the danger zone. Time is running out, as the next place that the fire will spread to is Seascape's bore hole. Alan lands Thunderbird 1 on Seascape.
Gordon goes down to the diving bell in Thunderbird 4. Seascape collapses even further and Alan has to lift Thunderbird 1 from the rig to prevent it from sliding into the ocean, Gordon cuts through the diving bell's cables with Thunderbird 4's laser beam equipment before clearing the debris, attaching magnetic grabs to hoist the bell to the surface and getting clear just as Seascape explodes in flames. Thunderbird 2 completes the rescue by picking the bell from the water with its magnetic grab.
The rest of the crew (at least 16) were safely lifted from the rig by World Navy Helijets.