In Cold Blood. It's a story you may by now know. What I liked about it was the "construction", that is, how Capote put the story together and told the story. When I finished it, I recall saying to myself - That's a damn well written book!
I second In Cold Blood. Great read.
Spoiler below? If so ignore if you haven’t read:
I read an interesting analysis on the book, later, which demonstrated that author Capote totally ignored the homosexual angle as the motivation for the beginning of the murders. The two murderers were homosexual partners in prison. When the feminine one of the two showed sexual interest in the young lady, the masculine one got jealous and murder-y. Made sense.