Sinkhole Surprise

From publisher blurb: Your trek across the frontier has been quite boring. With only nature and wild game to look at, you thought your career would be more exciting. A tremor and a loud roar is heard and the ground in front of you sinks in. A few more steps and you would have been done for! Peering inside the hole you notice hewn stones inside...a dungeon has opened up! This adventure setting was designed for 5th Edition AD&D for the Filbar Campaign, for three, third level PCs.