I haven't been following this. So Axel gets a text message saying someone is following him or something and accusing Axel of this or that? Then "Singer" decides he has a historic AP secret going back years and wants to meet Axel days after the text message to Axel.

And Axel is an AP who probably doesn't want to be identified.

So of course this is the part where the half naked girl decides to go into the basement by herself, even though she seems to have misplaced her dad's chainsaw. Or am I missing something? Do "Singer" and Axel know each other?