Leviathan Wakes, by James SA Corey
This is a nominee for best novel in the 2012 Hugo Awards.
The executive officer of an ice hauler ends up captain of the remainder of their crew after their ship is nuked by a stealth battleship. A detective ends up deep in an investigation he was supposed to ignore.
Holden, the sailor, wants to find out who nuked their ship and killed his friends, and when he investigates, he finds a piece of evidence linking the Mars fleet. This ignites the powder keg of conflict between the Belt and Mars.
Miller, a cop on Ceres, is told to find a girl and take her back to her parents. She'd run off and abandoned her family's wealth to help poor people in the Belt by joining the Outer Planets Alliance, a sort of IRA for the Kuiper Belt and beyond.
The conspiracy they uncover is far deeper than they expected.
This is a good old-fashioned space opera, albeit one in which they don't leave the solar system (because there's no FTL). If you like that sort of thing (and I do), this book should be right up your alley.