I'm about to GM On the Run this weekend as our first run, and my plan is to have Mr. J tell the players his employer got wind of a significant data haul, but he doesn't know anything about it except that its valuable to some people he considers his competitors. Mr. J needs them to get the haul, verify what's on it, find out as much as they can about what makes it valuable, and make sure no one else gets it.
His only lead is that he knows someone out there is trying to sell this haul, but he hasn't been asked to make an offer directly, so he needs the runners to start by putting their ear to the street. From there, everything proceeds as written.
From what I've read, I don't think this changes anything about any NPC's motivations or actions. Sure, if the shadowy employer knew what was on the disk, he'd know the runners could get more money elsewhere and never encourage them to find out what's on it, but I don't see any reason the shadowy employer needs to know what's on the disk. After all, if he got the offer email or knew what it was, why didn't he tell the runners who sent it instead of wasting their time tracking it down through Nabo? Or tell them about any of the various leads?
OR, maybe the shadowy employer is JB himself, and the whole thing is an elaborate test to see what the runners are made of for his future machinations, so there's no explanation necessary for why he does the convoluted things he's doing except that he wants to watch the runners work.
Disclaimer: I'm new to GMing Shadowrun to maybe I'm talking out of my rear end
