A girl falls out of the ceiling.
This is not a thing that happens on as many as several levels, but given that it's happening in the main reading area of the library, where enclavers stake out territory, and the library is quite populated at the moment, there's really no arguing that it didn't happen.
She's wearing a halter top and knee-length leggings and strappy sandals, her hair is loose and falls to her waist, and she looks about twenty. Leaving aside that nobody is supposed to fall out of the ceiling, this isn't somebody who expected to or had any reason to be in the Scholomance today.
She does look relatively disheveled; she has bruises and her hair is uncombed and her ankle has a faint burn scar encircling it. But that doesn't make any of this make any sense whatsoever.