The retro rockets fail on a manned mission to retrieve matter from a solar prominence, putting the spaceship on a collision course with the Sun. Thunderbird 3 and Thunderbird 2 are sent on a dual mission to transmit a radio signal that will remotely activate the Sun Probe's retros.
| Actor | Role |
|---|---|
 Peter DyneleyJeff Tracy / Professor Heinz Bodman (voice) | Jeff Tracy / Professor Heinz Bodman (voice) |
 Shane RimmerScott Tracy (voice) | Scott Tracy (voice) |
 David HollidayVirgil Tracy (voice) | Virgil Tracy (voice) |
 Matt ZimmermanAlan Tracy / TV Reporter (voice) | Alan Tracy / TV Reporter (voice) |
 David GrahamGordon Tracy / Brains / Kyrano / Solarnaut Asher / Braman (voice) | Gordon Tracy / Brains / Kyrano / Solarnaut Asher / Braman (voice) |
 Ray BarrettColonel Harris / Colonel Benson (voice) | Colonel Harris / Colonel Benson (voice) |
 Christine FinnTin-Tin Kyrano (voice) | Tin-Tin Kyrano (voice) |
| JJohn TateSolarnaut Camp (voice) (uncredited) | Solarnaut Camp (voice) (uncredited) |