'Deep Heat' by Albert Fennell

After a robot probe inexplicably disappears, the Stingray crew is ordered to investigate. Troy, Phones and Marine follow the trail to the base of a volcano, which is about to erupt. However, Troy and Phones are then captured by two survivors of a destroyed city, who tie them up and leave them behind while they head for Stingray so that they can escape the imminent destruction…

Don Mason (Captain Troy Tempest), Robert Easton (Lieutenant George Lee ‘Phones’ Sheridan / Agent X20), Lois Maxwell (Lieutenant Atlanta Shore), Ray Barrett (Commander Sam Shore / Lieutenant Fisher / Titan / Fragil), David Graham (Turata / Tracking Station)

Directed by John Kelly
Produced by Gerry Anderson

TX (UK): 7th February 1965

Notes:
*Featuring Captain Troy Tempest, Lieutenant George Lee 'Phones' Sheridan, Commander Sam Shore, Lieutenant Atlanta Shore, Lieutenant Fisher and Marina