The titular Red Horse carved into the flank of the large hill in Strond Valley serves as a door to the World Below. Years before the events of Runemarks, it was sealed with a series of nine Runes, locking people out. The Horse measures around two hundred feet from tip to tail.
Because the Horse was carved so long ago, and has clear magical properties the locals believed that it is the home of demons, is evil, and over all should be avoided. There were many rumors about the Horse: that it held gold, that opening it would bring something terrible, and more ideas along those lines.
The maze-like passages closer to the sun are now infested by Goblins who call Loki the Captain and fill rooms and tunnels with junk and loot. They are particularly fond of strong ale but are not particular about their food.
Further down, however, the tunnels are home only to rats the size of small dogs, and cockroaches.