Little Troubles Come In Big Packages

From publisher burb:

Ages ago an advanced civilization developed a technology that allowed them to reduce things, both inanimate objects and living creatures, down to less than 2% of their original size. Thought to be a perfect way to store materials for future use, it was soon learned that, after a short period of time, the process could not be reversed and whatever was “shrunk” remained that sized indefinitely.

While traveling through a heavily forested section of a valley, the characters happen upon a small building, the size of a child’s dollhouse, partially ruined by fire...