The Fireball XL5 gang are sent (further into space than anyone's been before) to investigate. On arrival Steve, Matt and Venus fly down to the planet in Fireball Jr (XL5's detachable front section), but crash-land thanks to Triad's ultra-high gravity. As you might expect, everything on Triad's enormous, and the effect of giant vegetation's achieved very simply by the use of normal-sized plants.
That's the flora. The giant fauna of Triad's represented by a risible back-projected lion who gives Matt the fright of his life.
Our heroes use their jet packs (or whatever the technical name is) to escape into the trees, only to be plucked out of them by giant (real) hands that grab them as if they were, well, puppets. The "Planet of Giants" storyline was old hat even back in 1963, but as in this case it works in reverse to how it would in a live-action show (the actual size props are the giant ones) it's really quite charming.
The owners of the hands are a pair of big friendly giants named Snaff and Graff (actually, Snaff bears a passing resemblance to Quentin Blake's BFG) who together comprise the personnel of Triad's space programme (yes, by a remarkable coincidence they call the planet Triad too). Venus's verdict: "They're real cute!"
The vast explosions that brought the Fireball crew to Triad were failed attempts at sending a rocket into space - Snaff and Graff just haven't been able to get the fuel formula right for the planet's gravity. Obviously not operating under any sort of Prime Directive, Matt cheerfully agrees to work out how they can get into space in exchange for enough fuel to get back to XL5.
Fun though it is in Fireball XL5's inimitably goofy way, there's a real lack of drama or jeopardy in this episode. There's an absolutely ridiculous filler bit where Matt, Venus and Steve stand around in the Triad lab chatting about what Robert and Zoonie might be getting up to back at the ship (complete with impressions), followed by a scene on board ship showing them doing exactly as predicted (exactly what happens in every episode: Zoonie perplexing Robert with his sinister catchphrase "Welcome hooooome").
The closest we get to suspense is the possibility that Steve, Matt and Venus might not get back to the ship in time to feed Zoonie. I don't know how popular the pop-eyed space sloth was with the show's young viewers, but I can't be the only person who would have been quite happy for him to starve.
The nail-biting action of The Triads is all here for you to enjoy:
And finally, here's this week's number 1 single. The Shadows are still in the top spot but this time with a Cliffless instrumental. Dance on, everyone!