Help needed Getting Voidwalker questFollow

Hi

I'm a lvl 10 undead warlock and am try to do the quest 'Creature of the Void' given by Carendin Halgar in the undercity. I am having difficulty finding 'Egalins Grimoire' which is needed to complete it. It says it is being held by the Scarlet Crusaders in the tower west of Brill, however I have been to the tower just past Solliden Farmstead and cant find it, Any ideas or help on this would be appreciated.

Also it appears that your looking for a guy.. the quest requires that you get a journal from the chest inside the tower. Just kill the 2 Humans in the tower and open the chest. Then complete the quest.