BANGKOK — Most of us can read about sex trafficking with a sense of detachment. It is only when we see its results up close that we are forced to confront the full extent of its horror.

Nana Plaza is one of several “red light” districts in Bangkok. It is less than two blocks from my upscale hotel, but worlds away from it, a distance, you could say, separating Heaven from Hell. Girls — and that’s what many of them are — wear almost nothing. They are there to please. My guide points out a three-story structure. “The higher you go,” he says, “the raunchier it gets.” It looks raunchy enough on the ground floor.