You should have 4 marked locations in the map after underlining the symbols and doing the map marking.
Then you look at the marked map and right click all 4. Howard should wonder about the names.
You progress then doing Clarke's house and another nightmare.
Do Ivar's cottage and find out about Wellworth/Wholestone.
Do EB's house and phone call.
Now you can check the book in Nolder's Office and find out about Wollsprey/Windlapse. BTW - you need to have underlined The Tomb clue in Ivar's cottage for this.
That is the trigger - you have to have finished Braunbell's place first before you can do this marking.