Brief description to get you going.
The first two floors are a legitimate buissness. The third floor has a small legitimate part - a storage room, but then there is an entrance for its illegal (or just secret) part of a pixie farm. Inside there is a large matrix of slotted up, small critters all connected to a central hive computers, as well as aquarium to 'manufacture' these critters. This is top notch technology with clearly fortune in R&D. In addition there are two discrete exits from the facility - the first one leads to the sewers and the second one to a small nearby parking lot. Plenty of effort was done to conceal these exits/entrances to the compound and it seems like one was used for supply and the other for distribution.
The Mafia is going to take over the legal part of the operation and UCAS officials are going to remove what you have in the basement leaving it empty and barren. Your reward of the run will be a form of 'trust fund'.
That is you will receive a certain amount of cash every month for your share in the operation as well as a free lifestyle in an underground bunker. Which will start as a low lifestyle but you can upgrade it if you feel like it. I was thinking that the Mafia has an interest in you hanging out in there for security because they can no longer afford security like the facility had. So if you happen to be nearby if things go south - it is a big plus for them.
(Which is why they are going to leave the third floor minus the storage room) to your own use.)
Initially I planned here some social heavy and politics/intrigue episode - but our face character bamfed and while I have an NPC face it seems odd to give so much focus to a scene that revolves around an NPC - so I think that we will just fast forward a bit to the future and conclude these events as the aftermath of the run.