From the back of the book:
Beyond the Inner Sea lie the High Mountains of the Holmgard, the Roof of the World. Here the country is wild, and dangerous, sparsely settled by barbarians, dwarves, and the occasional mad wizard. It is a hard land of narrow paths, deep canyons, cliffs without purchase; a land of snow and ice that offers little comfort for those who risk her high walks. It is a land of giants where giants once roosted, where dwarves built homes and dungeons. It is a land wholly forgotten but rich in lost treasures that echo a world long gone. It is one rich in adventure, filled with wealth beyond imagining and glory for those who do not fall.
Beyond the mountains lies the Gottland, the land without gods. This too is a land of imagined treasures, where giants, trolls, and gods with cloven feet have walked for countless years. Many venture here, but only a few realize the dream of wealth everlasting for it is a hard place of primordial violence, ancient magics, and one of the last vestiges of the Horned God's Winter.
Of the Horned God's Winter is a series of loosely connected adventures that take the characters from the sea town of Capistria, through the Holgrad Mountains and down into the Gottland. Along its path, the characters may, at the CK's discretion, encounter rune magic, either for their Rune Mark or for the character wishing to become one. The 15 adventures are designed to play alone or or as part of a broader campaign arc. Each adventure is written such that the enterprising CK can add their own adventures to the mix.
Of the Horned God's Winter is designed for a party of 4-6 characters of 4th-7th level. It includes overland adventures, sea adventures, dungeon, and castle.