On a May morning in 1902, the "Paris of the Caribbean" was wiped out in minutes. Saint-Pierre, Martinique, a sophisticated harbor city of up to 30,000 people, was annihilated by Mount Pelee in the deadliest volcanic disaster of the 20th century. Three known survivors emerged from the ruins, one of them saved by the thick walls of a poorly ventilated dungeon cell.

Drawing on volcanology reports, historical accounts, and modern seismic data, this episode profiles the geological giant itself: the subduction-zone pressure valve in an 850-kilometer planetary crumple zone, the acid-rotted flank that collapsed into the sea 25,000 years ago, and the two years of warnings the city ignored before the pyroclastic surge. It ends in the strange present, where a UNESCO World Heritage designation is drawing tourist crowds to a mountain that still rumbles with hundreds of deep earthquakes a month.

• Three survivors out of 30,000, and why a jail cell became the dividing line between life and death
• The subduction engine: how the Caribbean plate's collision built Pelee and its notorious volcanic family
• Hydrothermal rot and sector collapse: the mountain that hollowed itself out with battery acid
• Two years of alarm bells: the venting, the tremors, and why a city of 30,000 stayed put
• Destruction and rebirth: the volcano frog, the literature of trauma, and a restless UNESCO site today