No not impossible that she's telling the truth, just a bit unlikely. And generally, Butcher hasn't had much in the way of unlikely things happen.
I mean, to save up money like that & never get a decent place to live, seems odd. To me it seems like dream job & just walking away seems like a big deal. Yet Marci did it without any second thought?
Then 2 characters act like there might be something up with her? Another red flag for me.
All that means for me, is that I intend to keep an eye on her. She might be legit, bit I don't think so. As for who's pulling her strings, no idea.