[Styx's head shake is confirmation enough that she understands the situation correctly. This woman is incredibly defensive--comically so--and has basically given herself away. He even goes so far as to insinuate that she's the guilty party.

A part of Alice appreciates his hesitance to call her out directly. It's a kind way of handling things, regardless of his reasons. He's giving her an out.

As someone experienced with this sort of thing (and the necessity of getting paid to do it), however, Alice chooses to be more direct.]

I'm afraid that's exactly what we're accusing you of, ma'am. You're a very bad liar, and I think your prank of Mrs. Greenestone has gone far enough.

[She pauses, giving the woman time to respond. In response, Alice and Styx are treated to a face journey: first shock (likely at herself), then indignance, then a small noise as she starts to defend herself, and finally a sigh. The witch is caught, and she knows it.]

"I didn't mean anything by it, really. I thought it would be funny, and it was at first...

"What do you plan to do with me?"

[In response, Alice taps her chin lightly.]

Let me confer with my associate.

[At that, she crouches below the window and pulls Styx down with her.]

Well? What do you think we should do?