Future Peril

 

"Through your collective efforts you finally force the massive door open. Beyond, stretching far past the reach of your lanterns, is a dark, silent tunnel. However, it is not completely featureless. In the distance you see something. As your eyes adjust you realize it is a glowing skull and crossbones."

 

Congratulations. Your role-playing group of atechnical future primitives have just found an ancient radioactive waste repository. :-)