From the Introduction:
The Stalk, like so many of the adventures crafted for the Original Campaign (OC), was meant as a diversified challenge for our veteran players. There was no exact placement for it within the campaign world, and for good reason: the players had become wary of the dungeons we had contrived with all their inherent dangers and had opted instead to do outdoor adventures.
A small "outdoor dungeon" (for characters of 9-12th level) that takes place in the vines of a giant plant.
This is not a bound book -- it's a set of 13 loose pages (plus two heavier-stock cover pages) in a plastic bag. The last three pages scans of Kuntz's original handwritten adventure from the 1975.