As much as i know D&D is not the system for this, I am running an urban campaign and I feel that this may need to come up.

There is no way to hold people (adventurers) at crossbow-point/gun-point etc.

For example, a NPC rogue couldnt go up to the 6th level PC from behind, press a loaded hand-crossbow against the PC's neck and hold him hostage or demand something.

If the rogue fired that crossbow, even if i made it count as a coup de gras, chances are the PC would survive a bolt through the neck/temple, etc. And then just turn around and kill their attacker.

I feel like there should be some way for this sort of thing, or different variations on this, to be done.

My issue is that If i create rules for doing it, my players will instantly abuse them.

Any ideas on how to make this work? Opposed Grapple check type things? Only against flatfooted opponents not in combat?

Thanks.