Batman: The Long Halloween
written by Jeph Loeb; illustrated by Tim Sale
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Caution: potential spoilers.
This was a 13-issue miniseries that started in December of 1996 and ran through December of 1997, but it's set shortly after Year One, which came out ten years earlier (and which I expect was itself set some years before the timeframe of the other Batman stories that were being published at that time). Anyway, I've been aware of "The Long Halloween," at least in collected form, for at least a decade now, but I finally got around to buying it in October 2012. Read it over the course of about a week, with the last three chapters being read on Halloween. Although I should say, the overall story isn't particularly Halloweeny.
The first of the story's thirteen chapters begins in June, and runs through October. It's on Halloween that Johnny Viti, the nephew of Carmine "The Roman" Falcone, was killed. Over the course of the next year, various members of the Roman's criminal organization are killed, each on a different holiday. So the press starts calling the unknown killer "Holiday." Batman, Captain James Cordon, and District Attorney Harvey Dent, all want to figure out who Holiday is and stop him, though Dent doesn't seem particularly upset by the fact that mobsters are being killed. So there is some suspicion that he himself might be Holiday. Meanwhile, there are any number of other potential suspects, and of course the Roman is very eager to find out who Holiday is, and stop him (or her). Another important character is Sal "Boss" Maroni, the Roman's chief rival for control of Gotham. Naturally, there are also plenty of wild cards in the form of Gotham's various costumed villains. (Generally the mob doesn't associate with them, but the Roman will eventually hire some of them in his quest to uncover Holiday.) And Batman has lots of run-ins with Catwoman, while Bruce Wayne is apparently dating Selina Kyle (who looks very different than she did in Year One, btw).
There are plenty of other characters I should mention, like Harvey's wife, Gilda. The Roman's sister, Carla Viti (Johnny's mother); incidentally, there's a Falcone family tree in the back of the book that makes it look like Carla is the Roman's daughter, so... someone messed that up. Then there's the Roman's son, Alberto Falcone, and daughter, Sofia Gigante. And there is a flashback at one point to a night when Bruce was a kid, and his father was forced to save the life of the Roman (whose own father was Gotham's top mob boss, at the time). Anyway, lots of stuff happens in the course of the story, including Dent's transformation into the villain Two-Face. And, um... I won't say who eventually turns out to be Holiday, but my own guess was at least partially correct. And, well, it was all just a pretty decent story, so I'm glad I've finally read it. And I hope I'm not forgetting to say anything important.