The PCs are likely are going to try to get into a safehouse of the local thieves' guild in the next two sessions. The setting is Ptolus, using the D&D 5E rules.
The safehouse in question is in a lower middle class region on the surface, but it has another entrance to the vast dungeon systems beneath the city. This, in itself, is not unusual - the bedrock on which the city stands is filled with tunnels and long-forgotten vaults. But while most house owners just try to brick those passages over, the thieves' guild actually uses these passages for their business dealings.
And I need some ideas on both what might be inside the premises, and what kinds of systems they use to secure the safehouse. The PCs will likely be coming from the "dungeon" side, and this is the kind of city where criminals expect inconvenient adventurers to pop up in all sorts of places.
I've already determined that the location includes:
- a vampire ally of the guild
- some cells for prisoners who get interrogated for information
- a bunch of drugs for resale
Any other ideas? The party consists of four 8th level characters, if this helps.
There were some naturally-occurring caves, but also the following:
The whole dungeon system has developed over the course of more than 8,000 years. The general inclination of the citizens above is to wall off any entrances they find, and otherwise let adventurers deal with it. (This is another unique aspect about this city - it's the only one on the continent which has a professional class of adventurers.)
As for the Thieves' Guild, they tend to grease a lot of palms in the city watch, so they don't have to worry much from law enforcement unless they do something too blatant. However, there is a new criminal organization which is giving them a lot of trouble, and there are a lot of adventurers around, so they do have reasons to take their security seriously.
The guild have mages in their employ who could help with magical security, but none of them is present in this safe house.