Chthonic is a game that plunges modern-day character from the financially challenged mining town of Chthonic Falls into an underground world or Orcs, Goblins, Trolls and magic. Initially, everything is extremely foreign, and they find themselves fighting monsters, but soon one has to ask the question "Who are the monsters here?" as the characters find themselves changing in unexpected ways. As they make their way back to the surface and the world they think they know, they will inevitably bring things with them that are likely to change that world forever.

Thus far, the charcters were plunged into the darkness when they were, for a variety of reasons, in a mine site. A local school teacher, Erica, was meeting with her boyfriend, whilst the local jeweller was seeking new gemstones to fix and sell in her local shop. Mining engineer Nicolas, mine electrician Gordon and miners Shaun and Alan were simply going about their business as usual, though this was unusual business, but business none-the-less for the local trapper Billy, who had been asked to deal with the local racoon problem. Similarly with Deputy Bachmann, a local police officer, had come into the mine on official business.

Then the collapse happened, and all their worlds were changed. Dumped mercifully into an underground lake, they did survive. Well most of them did. A couple of miners bodies were found once they got to dry ground and found some light. This location seemed to be an old cave, probably used by bootleggers 100 years ago, but abandoned since then. They found some torches and a couple of old weapons, but a dispute arising after finding items on a 30 year old body when Deputy Bachmann drew his gun to assert authority wnet badly wrong, resulting in Alan being killed and Bachmann then committing suicide.

Concerned about further collapse, the group pooled resources and pressed on.The soon found Gordon, who had fallen into a different section. Crossing an underground lake, they came to a door that did not seem to be human construction. When their noise disturbed some ugly giants within, they soon found themselves potentially on the menu, and Bachmanns gun became decisive in ensuring their survival. And in releasing a strange, green humanoid prisoner that seemed to have some incredible way, like magic, of enabling the group to understand him, despite the obvious fact that he did not know English (or Spanish...).

Searching around, they allowed the greenskinned humanoid to return home after he directed them to food and where he thought the way home was (and stole an old pistol!) The group rested and tried the food that was suggested, eventually finding that the uncooked berries were the only thing that could be eaten without becoming sick. But the berries had other effects, transforming the eaters into something...else. Shaun and Erica gre pointy ears and developed magical talents, and Gordon grew bigger and stronger, somewhat changing in appearance more than the other 2. The other three decided to try fasting instead.

Preparing to move on after Shaun finally woke up, they were awoken by strange small green toothy humanoids with crossbows and spears. Whilst Gordon was badly injured, Billy was able to strike 3 of them down, two fatally, and scare the rest away. The surviving greenskin and Gordon were patched up (taking off as soon as it could), and the group headed off, only to be ambushed by the remaining greenskins and their friends. After a bloody fight that has seen Billy badly injured and many small greenskinned humanoids killed, injured or having fled, the group discovers that the injured member who crawled back to them was just in time for dinner...and he was on the menu!