Hellstone tells the story of a dark, mystic stone, which has the power to open a temporary gate to hell as long as it is fed with the blood of the human being possessing the stone. An occult, satanic covenant is trying to summon a demon and open a permanent gate to the underworld with the help of the stone to merge the dimension of hell and our reality as we know it for that hell will rule over the earth. Between this remorseless covenant and the literal gates of hell stands one man who becomes a witness of a violent satanic ritual, and from this point he is the only one who is able to stop the forces of evil by using the infernal powers of the dark stone by himself.