Alan and Grandma are made to climb up on to the girders of the bridge, then with a sonic wave generator in place, Gomez and Johnny steal the BR2, leaving the Tracys to their fate. Thunderbird 2 arrives, and using a Neutralizer Tractor, Brains neutralizes the sonic wave generator to enable Virgil Tracy to manoeuvre a Jet-Air Transporter on to the bridge underneath Alan and Grandma.