Kiera unlocked the door to the classroom that the club was using as a workshop. Fiona, Claire, and six other oculomancers shuffled inside. The room was pitch black, but none of the oculomancers needed any light to see.

Every book in the room was replaced with a corrected version. Every little scrap of paper was modified in some way, using the author's own handwriting. Pressure tables, material strength tables, temperature, measurements, wing shapes and angles... everything that looked like a number was replaced with a different number. The oculomancers had some devious method of changing those numbers so that they would still produce good results for some inputs but not for others.

"Pay attention to their methods, my apprentice," Fiona said. "These women are professionals. They were personally trained by Lin, also known as Lin the Historian. We rely a lot on Lin to make corrections to history books and the like."

"This seems like a lot of effort," Kiera said. "In retrospect it might have been a good idea to..." She didn't want to say it.

"Knives in the dark?" Claire asked.

"And change public records so that the were never born," Fiona added. "Yes, my apprentice. That is one approach. However if people start talking about how inventors are being murdered, it may spur even more interest in flying machines than we can handle without it becoming too expensive. I have been doing this a long time, and I am not too concerned. I am happy that you were able to see it for yourself."

"See what?" Kiera asked.

"Just how easy it is to invent the flying machine," Fiona said. "I want you to understand that technological advancement happens very rapidly. You should be afraid."

"I am," Kiera said. "Are you going to kill those boys?"

"I might be willing," Claire said, "this city belongs to my family, after all. I think Seth is very cute though. Maybe we should kill Quinn first and see if the club falls apart?"

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"No," Fiona said. "There is still a lesson that I wish to teach my apprentice."

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The next morning when Quinn woke up he realized that it was quite late in the morning. He had likely missed all his morning classes. He also had a hangover.

It was a night to remember, though Quinn didn't quite remember all of it. There were girls. Very pretty and very expensive girls. Quinn also learned that Vince seemed to prefer the male courtesans, which in retrospect seem very unsurprising.

After classes ended the club met in the workshop. Kiera and her teenager friend were absent for some reason. That wasn't too much of a problem, Quinn was beginning to suspect that the Aden Princess really did not like him.

What was a problem though, one which befuddled even Bjorn, was just how any mistakes they began to find in their notes.

It was as if the laws of physics had suddenly been upended overnight. They found dozens of mistakes in their designs. Quinn was shocked that the craft even flew and didn't break apart instantly. Even the textbooks seemed to disagree on basic facts that the club members had taken for granted.

Quinn thought that his hangover might be the problem. Everyone was clearly frustrated, though everyone had also been out drinking the night before.

Something was nagging at Quinn. He double, triple checked his notes. They were definitely written in his own handwriting. The invoices from the carpenter's guild had his signature. The textbooks still had his notes in the margins on the correct pages.

However, Kiera and Claire were the only ones in the club who did not go into Hightown with the rest of them the night before. So where did they go? And, disturbingly, they were both oculomancers now. Maxius had warned him to avoid oculomancers.

"Boys," Quinn said. "Do you remember that piece of paper that Kiera gave us last night?"

"It looked like a children's drawing," Seth said. "Just a bunch of scribbles."

"I have a theory." Quinn said.

Bjorn perked up. He was clearly disturbed by the state of his calculations.

"What if oculomancers can copy handwriting perfectly?" Quinn asked.

"That might be possible, but they would also need to be able to make perfect copies of textbooks, notes, design diagrams, pressure tables, and..." Bjorn trailed off.

"I don't think we can rule it out as a possibility," Quinn said.

"Alright," Seth announced to the club. "I have an idea. In the best case, we can't trust our past selves to not make mistakes. In the worst case, Keira and Claire are actively trying to sabotage the club, which, by the way, we don't have evidence of. But right now, we do have a working flying machine, and even if we wake up every day assuming that our notes are bogus, we can still make improvements to the flying machine and test those improvements against reality directly."