I think we need to talk about Pigeon Street. For anyone who wasn't a small child in early-80s Britain, Pigeon Street was an animated series about the various residents of the titular city street. It had a colourful cast of characters, such as Clara the truck driver, Mr. Jupiter the astronomer, William the window cleaner, Mr. Baskerville the detective, and all their friends and neighbours. The street had actual pigeons too, of course, who occasionally played some minor role in the plot but mostly just fluttered around making cooing noises.
Many of the characters had their own theme songs, which ranged from catchy to the kind of earworm that stays with you for life (I'm willing to bet that everyone of a certain age has had the "Long-distance Clara" song going around in their heads since the last paragraph). Each episode featured a couple of these songs woven into a connecting plotline. This would typically be a slice of everyday life, with a few of the characters going to work, helping each other out, and dealing with the little problems of human existence. Simple, charming little stories about a friendly urban community.
Here, watch a couple of episodes so you can see what it's like:
Episode 1: "All In a Day's Work"
Episode 6: "Pigeon Post"
And then there was the episode "A Light in the Sky". This one starts out normal. The pigeons fly around a bit. Reg the street sweeper has his leaf pile scattered by Watson the dog. There's a song about Mr. Baskerville and Mr. Jupiter. Then, a few minutes in, it takes a sudden swerve into the bizarre.
The residents are puzzled and disturbed by a twinkling, dancing light in the evening sky. They stare and chase after it. It disappears after luring all the characters to the top of a tower block. The next day, they show lingering confusion and strange behaviour. The light is never explained, even in the frankly creepy song that ends the episode. It's just some unknowable, sanity-challenging entity that human minds cannot comprehend.
It's not even as though this happened when the creators ran out of ideas. This was episode 2.
Let me tell you, it is distinctly unsettling as a pre-school child to have your cute cartoon show descend into cosmic horror. Decades later, I still can hear the weird piping sounds. The unearthly geometries still haunt my waking thoughts and seep into my dreams. What was the light in the sky? WHAT WAS THE LIGHT IN THE SKY?