"The Golden Horn" is a short story by science-fiction author Edward Pangborn, published in the Magazine of Fantasy & Science Fiction in 1962. It is set in a post-apocalyptic setting in what seems to be New England. The contents of this short story were expanded into a novel called "Davy", further developing the world.
Davy is a 14 year old indentured servant who doesn't have too many prospects in life. Neither does he have any close relationships, other than having a crush on an older girl who is a little flattered. Davy spends a lot of time wandering the woods near his farm, and we start to get hints about what is going on. He finds a picture scrawled on a cave wall, of an unusual figure. Since the story is told through Davy's own limited knowledge and experience, I wondered if this was an alien. But later we find out that it is a mutant (or "Mue"), presumably caused by the fallout after a nuclear war. We also find out that in this world, the Mue are exterminated by the ruling church, a harsh and authoritarian church that seems to be reacting against anything associated with the (eluded to) nuclear war. Davy befriends the Mue, and goes to its secret layer in the woods, where it shows him a lost relic from the past: the titular golden horn, a musical instrument that plays amazing music. Davy is tempted, and runs away with the horn, something that represents both his ability to think beyond the narrow confines of the world he was raised in, but also his ability to betray and hurt his newfound friend. Even after he feels remorse, the damage has already been done. The story is told from the viewpoint of Davy's life as an adult, so some things are foregone conclusions, but the story still illustrates the path there beautifully.
There are two things that are going on in this story that make it a good story. First is the character development. There is a formulation, sometimes overly glib or trite, that all stories start when something new enters the picture and forces development. "Man goes on a journey or stranger comes to town". And this book has both: the story manages to set-up Davy in his static position, and then describe, realistically, his process of maturation, first in overcoming his prejudice against the Mue, and then in giving into corruption and feeling remorse. But of course, that part could just be a young adult novel. The science-fiction elements, the world building, work as well as the story telling. We are introduced to a science-fiction world that is mysterious at first (it took me a while to realize this was happening on earth), but that establishes itself with laws that have internal consistency. As an added bonus, we manage to share this developing understanding of the world with our own narrator. This story has good character development, and also has a believable science-fiction world, which are both good things to have.
In another story in this collection, the disparate elements never tied together, and the character development didn't make sense in terms of the story. Both of these stories show the type of changes that were taking place in science-fiction in the early 1960s, but this one I feel made those developments much more accessible to the reader. However, that is just my opinion.