Bollocks, I accidentally closed the window too early.
They found out that it is the physical copies of the infected music which they need to reverse-engineer their cure to the infection. They have the Toccata, they have the the “I will kill again” (courtesy of hacking).
Hugo has got on to the Yule Ball Committee, and they plan to use the Yule Ball as the moment to enact their plan.
Additional: Hugo managed to get the janitor fired by leading him on a chase, ending up with him in the girl’s changing rooms covered in bras.
Hugo & Jonah broke into Mr Althorp’s office and found out he was likely infected by Karl Schmidt. Also his saxophone was skein-y. They went to have a look at the music room, but found it full of freaky music.