From the introduction:
This is a plot outline of a series of interlinked adventures across the planes, using the Infinite Staircase as a vehicle to connect them (at first at least). These can be played straight through, or they can be interspersed with side-quests, interludes or even (for the brave DM) interleaved with another campaign. In terms of Iron DM, this entry has little detail or "crunch" (DCs, NPCs, monsters) but instead forms a framework around which a DM can stretch the canvas of his imagination; favourite enemies, home-brew monsters, one-shot adventures and others are easily slotted into the overarching structure, with the PCs motivated forward by the encompassing plotline. The adventures are easily scaled to any level (within reason) by simply using higher or lower EL monsters, dungeons, wilderness encounters or social situations.