Beating head against desk. I wish I'd never read that. That woman is cruel to set us up for a mystery that engaging! Makes me want to drive down there and drag her back, throw her a hacksaw for the locks and shout: "REVEAL!!!"
Pandora's Box 2018.
You know, that might be a good marketing gimmick to SELL ones house... Have a door in the basement and put, two or three locks on it, tell the real estate to say they have no idea what it goes to or where the keys are for the locks... Hehe.
Or, if you want to get REALLY cruel, then you could have the agent mention something about one of the previous owners being a diamond smuggler...