Paradise Falls is the hub for Capital Wasteland slaver activities.
All, except for caged slaves, of its inhabitants are evil, so you don’t lose karma for killing them.
It is north of Arefu, but fast travel to Seneca Station if you can since the Arefu overpass terminates abruptly.
To gain entry:
a)Start and capture at least one slave for the Strictly Business quest.
c)Finish the quest Head of State in the slavers favor.
d)Go in guns blazing to kill the slavers.
or e) Speech check guard Grouse and pay 500 caps.