Here is the very basic plot idea, suggestions are loved to help design the setting and to make this plot really work.
There are raging fires that regularly sweeps through which never fully destroys the human's flesh, but the burn is felt long after the fire is extinguished.
These fires are caused by the demons who live and feed off of the fear of the human entries into hell. These demons feed off of the suffering and other negative emotions being experienced by the sinful humans.
However, a few pure souls have become trapped in hell. The punishment of hell was not meant for them, but the demons cherish these souls and cause them more pain and suffering.
These souls have not been forgotten by the angels of heaven. The problem is, however, that hell cannot be opened for any reason without risk of a demon breaking out into the human realm and manifesting into it's own physical body.
We can take this a lot of places, but please tell me what you think.