From the publisher's website:
"Strange doings are underfoot in the wild hills bordering the realm of decent and civilized folks. Villagers and cattle have gone missing; woodcutters have disappeared; misshapen beings have been seen shuffling through the forests. Some brave villagers have tracked a group of stolen oxen as far as the rocky banks of a small river in the hills. The trail disappeared down into a fissure in the limestone rock, where a fast-running stream plunges down to the dark caverns below. Gird your loins, stand behind the dwarf, and get ready to face The Pod-Caverns of the Sinister Shroom! Advanced Adventures #1: The Pod-Caverns of the Sinister Shroom is an adventure module designed for 6-8 adventurers of levels 2-4 and compatible with 1st Edition gaming."