Though aware that Ned and Joe will drown unless Gordon (voiced by David Graham) rescues them in "Thunderbird 4", the Tracys realise that without "Thunderbird 2" to airlift it to New York the submarine cannot reach the danger zone in time. However, Virgil suggests that "Thunderbird 4" could instead be transported by sea on board the "Sentinel". Jeff dispatches Gordon to rendezvous with the Navy for the 24-hour journey to New York. Meanwhile, Scott flies out to the disaster zone in "Thunderbird 1" to help the local authorities monitor Ned and Joe. A small bore hole is drilled into the rapidly-flooding cavern to supply the men with emergency underwater breathing equipment.