How about a random event + temporary amnesia? :D 

And the question still remains how horrifying we want to make it, because the plague is definitely going to put everything else in the background. As I said, for now I'd prefer to keep it to trying to describe and adapt to the everyday life of the people of that age. We'll start in a rural place so say hello to Mr Sheep who will keep you warm in the night time, and then probably have to travel to a city in search of someone rumoured to be a magician. That's the initial plan and from then on, we'll see what and when we feel like adding to it. :)