Hmmm. I'm conflicted. There is an interesting piece here, but there is too much overexplanation that makes the article read like an infodump of sort instead of a cohesive story. There's little soul to the characters' speech, and lines like 'However, everything in the market was ordinary and not very interesting, as every magical item was illegal and DTC should take care of it immediately' and 'I know Chester is with you and I know you do not want me to see him because I am part of the Department of Thaumaturgy Control now' feel immersion breaking: For the first one, that's something the setting itself explains. Why would Kat expect to find magical items in the market in the first place if they're illegal? And why would we expect the same? The last line, meanwhile, re-explains a point that we already understand. The previous 300 words were about this. Understandably, Horace knows this line is true, so why even mention it?
Stuff like this is sprinkled throughout the tale, and it made reading fairly obtuse.
This is a downvote, but I do wanna say that the core idea is really good! I'd recommend a rewrite after the con is done, focusing on making the piece read and feel more natural. As it stands, it's a difficult read.