Not sure I can say a lot without spoiling things,
It's fairly big regional sandbox. There are a great many towns of various sizes, adventuring areas both dungeon and wilderness. The background of the world/region is that for a long time a great winter covered the world due to the presence of a demonic being known as Unklar who ruled. Previously, the region was heavy with fey and the demi human races. About 100 years ago, Unklar was banished from the material plane. But his fortress remained and many of his very and not quite as powerful lieutenants went into hiding. Mankind moved in and have been trying to scrape together kingdoms, but they all squabble, as well as the demi-humans that remained or came back. It's a Borderland that still needs a lot of taming.
There is a bunch of material/sub plots in the books (like in NPC descriptions) and many adventuring areas that don't figure into the main, so you can totally ignore the main theme which involves the PC's piecing together the plots of men, monsters, those who may fit both categories., and ancient beings who are indifferent, or are undecided about what to do as man tries to civilize this Borderland region. But really you can grab the first few and do whatever- the later adventures, say A5 and beyond start to tie much heavier into the main plot (but still make fantastic dungeon/adventure locations to mod how you see fit). Eventually....well that's too much of a Spoiler. Sorry
Check them out on Drive-Thru or at
www.Trolllord.com.