It’s a fantastic work on the eternal struggle between Good and Evil that begins at the end of the 19th century

It’s a fantastic work on the eternal struggle between Good and Evil that begins
at the end of the 19th century, in London, with Digory and Polly Plummer, who became friends one summer afternoon. Digory had moved into his aunt and uncle’s house because of an illness that was killing his mother.
One afternoon at Polly’s house they decide to go over the rafters to get to a house that is supposed to be empty, they took a wrong door and they ran into Digory’s uncle: Andrew in his study, who was a malevolent and fearful old man, He considered himself a magician when he was just a simple apprentice who did not know how his spells worked.
Uncle Andrew decided to trick Polly into using a yellow ring that was on a table with other green ones which makes Polly disappear. Digory confused and angry asks Uncle Andrew for an explanation about what had happened to Polly, he begins to explain to Digory (without being sure of his own theory) that the yellow ring takes him to another world, while the green one brings it back “They only work,” he said, “if they’re actually touching your skin.”
Digory decides to go quickly to rescue Polly, so he decides to take the rings following the instructions of his uncle.