Methamphetamine - meth - is considered one of the hardest drugs to quit. This dangerous drug is ravaging rural communities and spreading its poison to major metropolitan areas and across international borders at an alarming rate. What makes this drug so powerful, addictive, and destructive?

National Geographic correspondent Lisa Ling investigates the meth epidemic to uncover the menace it poses to society and to find out why many are calling meth the world's most dangerous drug.