'Whistle For Danger' by Dennis Spooner

After Zoonie causes chaos in Space City, a furious Commander Shore locks the creature in a cage. Meanwhile, Steve, Matt and Venus are busy on the jungle planet of Floran, where the virulent plant disease Planetoid 3 has wiped out all the vegetation. Fireball XL5 is loaded with an Ellvium bomb, which, when exploded in the atmosphere, will destroy the disease and restore the plant life. However, two of the native Florans are suspicious – they capture the XL5 crew and imprison them in a castle’s high tower…

Paul Maxwell (Colonel Steve Zodiac), Sylvia Anderson (Doctor Venus), David Graham (Professor Matt Matic / Lieutenant 90 / Zoony the Lazoon / Floran 2), John Bluthal (Commander Zero / Floran 1 / Tannoy), Gerry Anderson (Robert the Robot)

Directed by John Kelly
Produced by Gerry Anderson
Associate Producer Reg Hill

TX (UK - ITV):
30th September 1963

Notes:
*Featuring Colonel Steve Zodiac, Venus, Professor Matt Matic, Commander Zero, Lieutenant 90 and Robert the Robot