It is estimated that there are 20 million commercial sex workers in India, and around 80% of these are victims of sex trafficking. Kidnapped or lured from their homes, these women and girls are forced to succumb to sexual exploitation as sex workers through a combination of coercion, torture, starvation and rape. 40% of these victims are adolescents and children. There is a demand side and a supply side to this deadly problem. The highly sensitive nature of the problem poses many research challenges. Our paper covers new understanding of the Demand & Supply sides. We will share how using innovative research tools informed by behavioural sciences provide new insights into decision making and how that is helping to reshape the strategies and campaigns to attack this deadly problem.