This windmill, located on the western hill in Twipeaks, was owned by Baldir Halfgray. When he passed away, he left it to his son Bodir Halfgray. In 002 - Bodir's missing treasure, Wazo negotiated with kenku squatters to access the treasure, and now they are its rightful owners.
Below the mill, through a trap door and down a ladder, there is a small room with four walls. The walls have these images:
Paintings by Giuseppe Arcimboldo
Above the third image, in golden dwarvish letters, is written,
All three images have been cut loose from the stone on the sides and bottom.
The wall with the third image has slid to the side. Behind it is a passage to another room.
In the center of that room is a large tree, growing out of a pile of dirt. Behind the tree is a glowing painting on a wall surface that has slid to the side. The painting looks like this:
Set of four photographs by Josh Friedman
Seasons - Threadleaf Japanese Maple Tree
Behind that wall is an open, empty chest.