2. Synthetics

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

3. Heroin

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.

4. Meth

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

5. Cannabis

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

6. Opioids

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