Something is wrong in hell. There is a distinct lack of new souls arriving and the big boss is not happy. You and a random band of other devils are send to earth to investigate and reinstate the flow of souls.
The system is based on a house ruled version of In Nomine developed by someone called Björn. The rules are simple and aimed at allowing feats and stunts worthy of the masters of hell while providing for surprises and creating an utter mess.