Warning:
Spoilers ahead. Of course, you already knew that from reading the node title.
Run around all
Myst Island turning on all
Marker Switches. Go to clock tower, set time to 2:40, form bridge, turn switch on. When you're done, turn the dock's switch off. Get
Dunny's white page.
Go to library. Enter fireplace, press button to lower panel. Enter the code of Page 158:
XX....XX
.XX.X.XX
X.X...XX
X..X..XX
XX..XX..
XXXXX.X.
Enter Dunny. (or
D'ni, it says Dunny in the credits). Give page to Atrus.
Congratulations!