This is a new mission in the Samhain 2013 event. It's a side mission started in the clubhouse of The League of Monster Slayers in Savage Coast. Upon completing this mission you will receive the item Danny's Book of Spooky Stories which you can use to read all of the spooky stories at any time.
This mission is listed under Kingsmouth Town when completed. Although it states it is repeatable, it is in fact not.
In the League of Monster Slayer clubhouse, there is a book of unfinished tales, with a note nearby. Read the note to find out more about this mysterious book.
Reward: 74,800 XP, Danny's Book of Spooky Stories, 5,000 Pax Romana
For this mission you need to collect 10 spooky stories on Solomon Island. All of these stories are collected through side missions on Solomon Island. Refer to the list below.
When you have collected all 10 stories, head back to the clubhouse to complete the book, then bring it to Danny in Kingsmouth Town to complete the mission.