Up near Doomcrag just before you reach the military camp you pass under an outcrop of rock. Around the back of the rock, (on the coastal side), is a bloodfiend named Klaandor. After you kill him you can take his diary, which contains the usual blurb about delivering it to a loved one named Vyctorell, but no quest started. After some searching I found Vyctorell, there was no prompt to give her the journal.
Looking online I found it was part of a quest called Last Words. I can only assume it was dropped from the finished version, or console version, (I'm on PS4).
I guessed there was a problem though when I got no quest, the book wasn't in quest items, (I think it was in materials), and had a value of 29 gold. In the end I sold it. As neither of us us wanted it what else was I supposed to do?