Stacey Dooley investigates the growing drug craze sweeping through Thailand. Ya-ba, a dangerous mix of methamphetamine and caffeine, has gripped the nation and unleashed a terrifying wave of violence among its users. She uncovers the human cost, visiting a shocking ward full of 'zombie' addicts, many of whom face the risk of long-term psychosis, and she also meets users who have started taking the drug as young as 12.

Stacey joins the Thai authorities as they try to fight back, joining patrols near the Burmese border and drug raids on Bangkok bars. In Bangkok, she discovers that dealers are starting to target western tourists and asks if this dangerous drug could soon claim its first victims amongst British tourists.