Despite its potential therapeutic benefits, MDMA is pushed into the shadows where it — along with synthetic analogs — have become popular party drugs.

Fox travels to Kenya, where she speaks to people living and working on the front lines of one of the world's newest and most profitable heroin routes.

Meth's global menace infects Myanmar, where complex politics and history have made it Southeast Asia's ground zero for production and distribution.

Despite the legalization of pot in California, roughly 80% of the state's cannabis sales still occur on the black market. Fox examines why.

Fox explores how highly addictive oxycodone continues to cause unprecedented destruction across America and even pushes addicts toward heroin.