The Doctor and Jo accidentally materialise inside a ‘miniscope’, a collection of human and alien lifeforms inside a machine used for amusement by a couple of travelling carnies.
There are two plot threads running parallel here: firstly, the carnies trying to entertain the emotionally muted inhabitants of the planet to which they’ve hitchhiked, which is funny because they have no concept of amusement and think the carnies are spies or part of an invasion fleet, and the situation grows more and more ridiculous.
Then we have the Doctor and Jo trapped on what initially seems like 1920s cruise ship, but is actually an artificial environment within the machine. This is also funny as the people get stuck in a loop and keep repeating the same sequence of events, repeatedly discovering the stowaways and then forgetting about them.
Things get interesting when deadly giant worm-like creatures from another part of machine escape and run amuck. Once the Doctor is able to escape the machine and return to full size, he then does his usual holier-than-thou routine to give the aliens a telling off for allowing the miniscope to be used, because they’ve been outlawed. Using the Tardis, they are able to deactivate the machine and return the creatures and people to their homes.
There’s certainly a colourful cast of characters in this. I like how the carnies’ attire is completely at odds with the aliens’ bland uniforms and grey faces. The looping events inside the machine were quite amusing, and the bits with the giant worms were well-realised and reminded me of the film Beetlejuice. Overall, I thought this was interesting and decent enough.
Noteworthy mention: apparently, the BBC experimented with new title music in this season, but it proved unpopular and they decided not to use it. For some reason, some versions of episode 2 of Carnival of Monsters mistakenly retain this new music. I can see why they didn’t use it, it sounds all sped up and boingy-boingy. Saying that, they’ve kept basically the same music for the last ten years, so I didn’t mind hearing something new.