Well, Midnight Tides is an entirely new story on an entirely new continent, with only one character that we've seen before, but time-wise it lasts from before GotM to most of the way through MoI.
Bonehunters follows HoC, sort of.
Reaper's Gale is a sequel to MT, but with many new characters.
Toll the Hounds... well, it goes back to the storyline of Memories of Ice, I suppose.
All very complicated, and you get a hoard of new characters introduced in every book
