Like a good murder mystery? One with Kakairu and detective Yamato especially? Then this is the fic for you 
I loved figuring out who “dun it” along with everyone else, and watch Kakashi and Iruka’s relationship evolve from the contention of their confrontation about the Chuunin exams to something romantic 
Fic on AO3: https://archiveofourown.org/works/5036728/chapters/11578411
Lol I literally just red this last week. It’s soooooo good.
Oh, I love this fic so, so much! It was one of the fics that got me back into the fandom, into reading and writing fic. 
I remember reading this, and being awed by the plotting! I also attempted to guess the whodunnit part but failed miserably ahahahah
excellent rec!!! would read it again now that u brought it up actually