Ernest Hemingway's first book on bullfighting, written in 1932; the other is The Dangerous Summer, written in the 1950's; both are non-fiction. Bullfighting crops up in his novels (The Sun Also Rises being the obvious example) and in some of his short fiction. To Hemingway, bullfighting connected in a profound way with his ideas about manhood: Something like Fight Club, but with real blood. It's not just a game; people sometimes die. It's not just theater; the outcome is uncertain, and people sometimes die.
Death in the Afternoon is Hemingway's attempt to explain the sport of bullfighting to a non-Spanish, English-speaking audience. He was a great fan, and he goes into it all in great detail. There's a lot more to it than just poking angry animals with sharp sticks. It's more like Kabuki (but with sharp sticks). It's a very elaborate and formalized ritual: The excitement comes from the fact that (unlike Easter Mass, for example) the main actor is a very large, angry, and dangerous animal. Hemingway sees it -- and he makes clear that the fans in Spain see it -- as tragedy in the dramatic sense (though not all that faithfully Aristotelian aside from observing the unities), as something more profound and significant than a mere "sport". "Aficionado" doesn't just mean "enthusiast"; it signifies "passion".
Hemingway also has a lot to say about style and technique.
Saith Ernie: "It is intended as an introduction to the modern Spanish bullfight and attempts to explain that spectacle both emotionally and practically."
It's well worth reading if you're the kind of person who can read four hundred and eight-five pages in a row about bullfighting and stay interested. It's sort of like a John McPhee thing, but with big angry animals and sharp sticks. And damn little punctuation.