What if the easiest way to trap someone wasn't a weapon but a favor? This episode examines Charles Sobhraj, one of the most elusive serial killers of the 1970s, who hid behind the disguise of a charming gem dealer.

We trace his stateless, rejected childhood, his rise through charm and fraud, and his method of poisoning travelers on the hippie trail so he could nurse them back to health and secure their loyalty, before murder became his brutal form of risk management.

• How he weaponized gratitude to build a devoted clan of followers
• Stealing and altering victims' paper passports to cross borders
• Diplomat Herman Knippenberg's dossier of evidence
• His botched mass-poisoning of French students and capture
• The legal maneuver he used to stay in prison and dodge execution