'The Big Gun' by Alan Fennell

After Stingray destroys an attacking submarine, another soon arrives to threaten Marineville. Foiling the assault, Troy, Phones and Marina pursue the sub into a deep undersea tunnel and come across the city of Solarstar. As the high water pressure threatens to crush Stingray’s hull, it seems that nothing can stop the Solistans in their plan to destroy the West Coast of America…

Don Mason (Captain Troy Tempest / The Mighty Leader), Robert Easton (Lieutenant George Lee ‘Phones’ Sheridan / Agent X20 / Korda), Lois Maxwell (Lieutenant Atlanta Shore / Tracking Station), Ray Barrett (Commander Sam Shore / Lieutenant Fisher / Titan / Mauritimus)

Directed by David Elliott
Produced by Gerry Anderson

TX (UK): 24th January 1965

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