'Tune of Danger' by Alan Fennell

Learning that a jazz group is to give a concert in the undersea city of Aphony, where Marina's father lives, Surface Agent X20 plants a bomb in the group’s bass. Troy learns of the plot to kill his friends, but before he can act, he is trapped inside a burning building - can he escape and reach the bomb in time..?

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)

Directed by John Kelly
Produced by Gerry Anderson

TX (UK): 27th December 1964

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