This adventure brings players investigation the disappears of local craftsmen. If they fallow the clues it will lead them through the outland city of Rigus to the plane of Acheron. They will then find the Iron fortress and the warlord Imperagon. The adventure describes one of the cubes named Kolyoral. There are multiple agents at play on the cube as well as the imposing fortress.
Sekarvu is a typical beholder. It spent much of its youth exploring underground realms and killing everything it found. One day, it came upon a large cavern filled with violet fungi. At the edge of the cavern, it found a small band of adventurers who had all but succumbed to the toxins of the fungi's tendrils. They offered little resistance to Sekarvu as it approached and began to feed on their still-writhing bodies. With its first bite, the beholder's life changed forever.