Thunderbird 1 sets down Thunderbird 2 sets down Scott Tracy Thunderbird 3 revving its engines in space Zero X about to take off
countdown begins

Thunderbirds 1 and 2 have arrived and are already near the launch apron as the mighty Zero X is assembled for blast off.

Lady Penelope listens intently as the St. Christopher signals come in, I . . . 2 . . . 3 . . . 4 . . . Then trouble. No signal is received from channel 5.

Immediately, Penelope contacts Scott Tracy who has set up his mobile control unit in Central Control. She explains that one of the crew members is either not wearing his St. Christopher . . . or an unauthorised person is aboard the Zero X.

The countdown cannot be delayed, for Thunder­bird 3 is already moving to a position in space where it is due to rendezvous with Zero X and to provide escort.

Scott acts fast. He enters the Zero X passenger compartment and confronts Dr. Grant. Suspicious, Thunderbird 1's pilot shoots out a hand and pulls a rubber mask from the man's face . . . revealing the hood.

Instantly, the evil villain menaces Scott with a gun and manages to escape to a waiting car.