"Lady Penelope invites Jeff Tracy for a vacation on her Australian ranch. Jeff reluctantly agrees and leaves Scott in command of International Rescue, after getting an update from John that a World Navy exercise is taking place in the Atlantic Ocean. This exercise involves warning a nearby mid-ocean drilling rig, the Seascape, whose crew chief, Frank Hooper, isn't pleased that the exercise involves firing nuclear warheads underwater. His concern proves justified when an errant nuclear torpedo detonates on the ocean floor and the resulting wave batters the rig. The swell settles and no damage is incurred, but that night a jet of fire erupts from the sea floor, the result of detonation of a gas pocket beneath of ocean floor. John hears radio calls about the fire jet, and Scott, after considerable agonizing over what to do, sends IR to plug the fire jet. The mission succeeds, but Jeff hears about it on the news and harangues Scott for getting involved. Penelope calms them both down, but the Seascape is further threatened when the gas pocket erupts in several areas; when Frank Hooper and his radioman man a diving sphere to examine damaged supports, they become trapped when the rig buckles and the sphere is buried on the sea floor. Now IR must work with the World Navy to evacuate the threatened rig and rescue Hooper and his radioman from the buried diving sphere."