From publisher blurb:
A System-Neutral Fantasy Roleplaying Game Setting
Three hundred years ago adventurers from the Vilburg Kingdom forayed into the untamed border region and quickly drove away isolated, unorganized bands of humanoids. Many settled here under the watchful eye of the Sentinel Knights and have prospered in their enterprises. But dark powers left from a wicked empire 2,000 years earlier still lurk in dark forests, forlorn ruins, and subterranean labyrinths...and a growing threat in the Ostmaur Peaks to the east threatens to overrun the apparent peace and prosperity in the Greydeep Marches.
This supplement contains a map of the Greydeep Marches; an outline of its major features; list of rumors; description of the Sentinel Knights; four new monsters; the Hammer & Tun, a tavern serving as a base of operations for adventurers; encounter tables for different regions within the Marches; three short adventures; and the Any-OSR Key, a system to easily convert stats in this supplement to your favorite OSR-style fantasy roleplaying game.