That's it.

The First time I did the "Reunions" quest nothing like this happened.

This time, however, right the first lead given by Dogmeat leads me to the Mayor's office, to a corner by an unusable exit. I cannot find any more clues elements nearby (such as the other previous times), so I am at a loss.

I would appreciate any lead on this (very painful to load a previous game - well, that would be quite a setback, considered my progress since this...)