The main setting module of Hârn contains two books; HârnWorld detailing the world of Kethira, coninent of Lythia and, in more detail, the island of Hârn and HârnDex and index of places, people and things in the isle of Hârn. Includes a large map of Hârn in colour.

The first book has three arctiles. One about the world of Kethira, it's climate, cultures, fauna, people and cosmology. The second article is about the largest continent, Lythia, with more details on cultures and places. The third article details the island of Hârn and it's history and current (year 720) situtation.

The second book, HârnDex, is an index of all things in Hârn, detailing (probably) every place mentioned in the map of Hârn, people, religions, cultures, powefull organisations and other things.

HârnWorld is probably one of the most detailed fantasy settings available and the basic setting books contain a lot of things rarely seen in other fantasy publications.