Gordon ventures deep into the Marianas trench to rescue a survey team, and ends up discovering an early International Rescue prototype vehicle once flown by Jeff Tracy. Gordon takes Thunderbird 4 down to save the crew and get a better look at the pro... (more)totype. But the survey ship, designed by The Mechanic, transforms and wrecks Thunderbird 4. Gordon is forced to abandon ship and seek refuge on his dad’s TV-21 plane. To save the survey crew, Gordon powers up the plane and manages to take it up to the surface.