Well, here's a quick summary of CATS (the musical, not the 2019 nightmare-from-Hell) that I just pulled up on my offline copy of Simple English Wikipedia on my Kiwix app - enjoy :>
"Every year, a tribe of cats known as the Jellicle Cats meet for the Jellicle Ball. At the Jellicle Ball, Old Deuteronomy, the leader of the tribe, chooses one cat to ascend to the Heaviside Lair to be reborn and return to a new life. Grizabella, an elderly (younger in some productions) glamour cat who left the Jellicle tribe's junkyard home, comes back to her tribe, but they shun her. While the other cats dance at the Jellicle Ball, Grizabella watches in the background. She performs a simple dance when the other cats leave called Memory, and sings about how she wants to be accepted. Old Deutoronomy sees this and sympathizes with her. In act two, Old Deuteronomy gets kidnapped by Macavity, a "mystery cat" who is the only true antagonist in the musical. As soon as he is successfully returned, it is time to choose who goes to the Heaviside Layer. Grizabella is chosen, and she is taken on a tire to fly into the Heaviside layer."
~ from Simple English Wikipedia