Sometime before Professor Layton and his assistant, Emmy had arrived to the town of Misthallery, Brock's House had been attacked and thoroughly destroyed by what was thought to be a Specter at the time. Althought that Brock had escaped the incident unscathed, he was left rather traumatized by the sudden attack, and a strange symbol was left as proof of said attack.
When the professor and Emmy first arrived here, they noticed the destroyed home. Before either of them could touch the odd symbol on the door, as was pointed out by Layton, Brock had appeared and said not to touch the symbol, lest they end up like him. Brock apparently used to complain about his home, but according to the homeowner, it was nothing compared to the ruins it was in then. The duo then leave the oddly positive man to his thoughts, though not before they find a wooden crate, thus reminding Layton of a puzzle.
Later, when the duo return with Luke Triton, Brock still seems to have not gotten over the shock of having lost his house, and apparently, nothing was missed the first time that Layton and Emmy had come through this area. It turns out the reason that Brock had escaped the attack unscathed is because of "The Oracle's" (who is, in actuality, Luke Triton) warning.