Prohibition Tunnels in LA
Not really sauce, but fits the discussion. I saw this earlier then consulted a TV show called Cities of the Underworld. There wasn't one that mentioned LA in the title, but I am watching one about the prohibition tunnels under Portland Or.
Then mention how they had trapped doors above that would open and the victim would fall through right into a cell below. They did this in buildings like bars were men were drunk. Anyone that was kidnapped, was taken underground.
Now just take that little bit of history and apply it to what might be going on in LA and all the human trafficking going on!