Help!

To the one who finds this: I have been taken by the Varangians, those cretins who seek to unlock the mysteries of Myrddin's experiments. Given my treatment at their hands, they won't use them for anything good. I overheard the guards when they thought I was asleep, and they intend to move me north to someplace called Riverside Keep. The leader here, Anton, is leaving tomorrow to go south, along with the notes of my travels. Damn me for a fool, but if they follow the trail back, they may locate what I think is Myrddin's true workshop. You must head south. There is a woman there, Caoimhe, an apprentice to an Antiquarian. She is an ally, and familiar with the magics of the island. If these bastards have passed anywhere near her, she will know about it and be able to guide you. You must recover my notebook and give it to her.