National Geographic Channel correspondent Lisa Ling uncovers the story of meth in "Explorer: World's Most Dangerous Drug" -- tracking the graphic world of the drug from the Pacific Northwest to the Midwest and overseas to Thailand.

Ling and her crew
Lisa Ling explores meth
 expose the world of traffickers, the dangerous impact of clandestine meth labs, and the heartbreaking stories of people addicted to meth. They also give a brief history of meth while showing meth's addictiveness -- and the devastating physical and emotional side effects it can have.

"Explorer: World's Most Dangerous Drug" premieres Wednesday, October 18 at 8 p.m. ET/PT on the National Geographic Channel. The show will also air on Wednesday, October 25 at 7 p.m. ET/PT.