From the publishers blurb:
The Pilgrimage of Hunger is a small cave system written for Veins of the Earth. The idea behind it is that it came into being in response to the hunger of the living, sentient minds and souls of the Veins. If it is the creation of cruel and dark gods, of a devil or demon, something from the Outer Dark or of some strange underworld godling of hunger that has devoured its own name is up to you as the GM. It is assumed that the existence and rites of the chapel are known to at least a few dwellers of the Veins in the wider area, and that those in the know make regular “pilgrimages” to the chapel (for the sake of survival).
Non of this is canon or official!