The Book of Haricanto is a book written by an ancient sorcerer from the Eastern Lands named Haricanto, and is found during the Ghosts Ahoy quest. It is one of three items that players must present to the Old Crone.
Players can find it on Dragontooth Island by starting one square west of the statue of Saradomin near the north-western peninsula and following the instructions on the treasure map. They must then dig with a spade to find the book.
Trivia
Upon giving the item to the Old Crone, any duplicates will be removed from the inventory or bank; however, completing the quest does not eliminate any duplicates.