This supplement for Four Against Darkness - Expanded Edition introduces additional tiles for caverns and fungal grottoes: natural chambers and tunnels with special rules. It includes two short adventures: Truffle Kerfuffle (a fungus gathering mission) and Underground Chicken Run (a diplomatic mission among morlocks). Also included, two long treasure tables and a few new spells. A copy of Four Against Darkness - Expanded Edition is required to play. IT IS NOT POSSIBLE TO PLAY THIS SUPPLEMENT WITH THE OLD EDITION.