When we hear the phrase "human trafficking," we often think of movement—that people are being trafficked, moved around, perhaps even from country to country. This is not necessarily the case. In some cases, human trafficking does not refer whatsoever to geographical location. People can be trafficked in their own hometown and even come home to their loved ones at the end of the day. These kinds of cases aren't what people usually imagine when they think of human trafficking—and they can make a strong subject for a paper that will deepen a reader's understanding of the issue.
In first-world countries, we often want to think that human trafficking is something far away from us, but that is simply not true. Research into "local" cases of human trafficking, as well as signs we can use to identify someone being trafficked, will definitely add to one's understanding of this horrible system.
I know that these are difficult topics to deal with, because we do not want to think of anyone being abused in the ways that these victims are, but educating yourself on the problem can lead to you being a part of the solution.