I seem to remember having to read a Rumor in Warjilis Bar to make it appear, but I could be mistaken.

If you're at the END of chapter 4, the only red location on the map should be Orbonne Monastery. Of course, Deep Dungeon is also a red place, but other than that, it should just be Orbonne.

Anyway, I'm leaning toward the Rumor at the bar thing, but I don't know for sure.