That dream was confirmation. I had completely lost my mind! 

I couldn't find Frank on my own, so I decided to search for Amanda instead, heading toward her room. With her help, perhaps I could get the guards on my side, and we could all hunt down Frank collectively. I would murder him myself if I had to, just like all my reflections suggested!

However, stopping Frank would only ensure he didn't get his hands on the necklace. He clearly did not know where it was. That meant I needed to find some other way to figure out who was currently in possession of it. The police wouldn't tell me; they had auctioned it off and were respecting the confidentiality of the buyer. And since I was out of money for the moment, I wouldn't be able to just pay a gigantic amount to get it back - I would have to steal it from whoever had it now. This whole situation was such a headache!