Fevre Dreams by George Martin
I thought the captain just a bit far on the stupid side and combining vampires with steamboats seemed a bit ... I don't know, childish?? But it was ultimately a story that pulled you in. Although some have called it as much a historical novel as a horror novel I didn't think the setting was quite detailed enough. But extreme injustice comes in at about 50% and one just doesn't want to stop reading until the injustice ends, which happens finally at the very end. Doesn't end as well as I would have liked, but I definitely seen worse. Definitely more of a page turner than I've read in quite a while.

I want an ideal of a very detailed setting that is still a page turner. Mervyn Peake for example had great detail and a story that's stuck with me very strongly, but it really wasn't a page turner. This became a page turner because of the level of injustice that occurs to adequately developed characters but I think there was more potential for bringing mid 19th century New Orleans to life.

One turns the pages in the beginning waiting for the Abner Marsh (the steamboat captain) to figure out the mystery of his "cocaptain", who's name I no longer remember. Not too long after he learns all, (that he's a vampire-like creature who's invented a drink whereby his fellows never need kill anyone again), the injustice begins which keeps us turning the pages.

It's a good formula. Maybe don't start the injustice too soon, wait till they care enough about the characters. Use mystery instead in the beginning.