Black and Blue, by Ian Rankin.
A dead boy leads to environmentalists, corruption, Bible John and Johnny Bible, and gallons and gallons of oil. And Rebus untangling it all, all while chased by an investigation re-opened on a case dead and gone with, eventually, no one left for the brass to come down on but him.
With the larger more complex novels, (Let it Bleed, perhaps, and definitely Black and Blue, and I note The Hanging Garden is about the same thickness as B&B), my reading pace slowed substantially, and I did have to go back and forth a couple times and say "who?" when I was reading. I have to admit, at the moment I prefer the earlier work. I think I might actually go back and re-read Knots and Crosses and Hide and Seek, which you swallow almost whole, before moving on to the next title in my stack from the library.
In the long run, I'll probably prefer the more complex later work, though. I'm a little put off from having seen the BBC adaptation of Black and Blue just last week, and there were substantial differences. And The Hanging Garden was broadcast this evening, so I might want to wait a week before opening up that one.