Most quests are more clear about what you need to find, where you need to go or who you need to talk to, so you probably will not get stuck like that again. Perhaps Edmond should have mentioned seeing a rat drag something away, through a hole in the east wall, that he had a nagging feeling was important. There are another couple cut scenes which do not get triggered unless you have the relevant quest, but you at least know roughly where you need to go for them.
