1. Start watching this video at about 18:45. (Tactical Retreat also works.)
2. After crossing the river, at about 20:00 in the video, instead of proceeding directly to Sacred Stone, climb up the mountain and enter the portal (unlike the fellow who made the video). It takes you to the chapel cellar. Be warned, however, that this breaks the Immaculate Trial quest and you'll never be able to complete it afterwards; however, this gets you books at level 3 instead of 4, which is a better reward.
I can't think of any way to word it more clearly than that.
