Interstate 20 starts on the west side of Texas and runs east to the Atlantic ocean, passing through Dallas along the way. The highway has lots of truck stops, some of which are known sites of prostitution, serial murders, or both. About once a month, always on a Wednesday, Dallas police show up at one of these spots for an unusual sting operation.

The cops round up the prostitutes, usually about a dozen of them, and bring them to an area set up with food, clothes, STD testing, and legal counsel. “They walk them over and say, ‘You would be going to jail if it was Tuesday. But it’s your lucky Wednesday’,” says Sara Katsanis, an associate in research