The Platonians are ruled over by King Bazan, who's had a lovely portrait done of himself by the same person who painted the Zanadu portraits in the previous episode:
Bazan intends to travel to Earth and trade some of his heaps of platinum for minerals the Platonians are desperately short of. Unfortunately, he has an implacable enemy, Ginarva (who we sadly never get to see) who thinks the best way to deal with the people of Earth would be to invade them, and who's engineered a series of assassination attempts. Clearly they're pretty rubbish assassination attempts, and given that the only other Platonian we meet in the episode is Bazan's servant, called (believe it or not) Volvo, it's not a massive shock when we find out who Ginarva's agent in the palace is.
The Fireball XL5 crew travel to Platonia to escort Bazan safely back to Earth, but while Steve and Venus are enjoying a seven course meal with the king, his nefarious servant deactivates Robert, the ship's long-suffering robot pilot, and then implants a bomb in his chest.
Steve Zodiac exposes Volvo as a baddie, and finds out there's a bomb aboard the ship somewhere, but sadly, despite the fact that he's transparent, nobody pays enough attention to poor Robert to notice the whacking great box in his chest area. Volvo gets thrown in Fireball's onboard Space Jail (yes, Space Jail).
The rotter escapes into space though, where for some unknown reason he's able to breathe perfectly well, he just floats about a bit. The Fireballers work out that he's going to be picked up by Ginarva's ship though: in Venus's memorable words, "Of course! Anyone ejecting into space without organising a pickup would be a tootie". They somewhat callously blow up the ship and everyone on it, and Steve ventures out to bring back Volvo - but will he reveal where the bomb is in time?
One thing that gets increasingly disconcerting throughout this episode is the amount of close-ups of real human hands wearing gloves to make them look like puppet hands. It's all a bit creepy.
Like all the episodes of Fireball XL5 I've seen so far, I think Planet of Platonia is adorable in its silliness. You can watch it here and see what you think:
And finally, what's at the top of the charts this week? Well, it's still Cliff Richard and the Shadows. Here are both the A-sides of their single: