Nat Geo HD Lethal Link: Three disasters are forensically dissected, from Challenger's fatal launch to a cable car tragedy and an ice rink roof collapse. (S2, ep 5) 7+ 2026-08-15 Seconds from Disaster. Looks at the 1999 Paddington train crash. Who was at fault? And could the devastating collision that killed 31 people have been avoided? 7+ 2026-08-15 Underground Cities and Secret Chambers: From underground churches to carved sacred chambers, hidden sites show how ancient communities created refuges for faith. (S1, ep 1) 7+ 2026-08-15 Crystal Cathedrals and Buried Bunkers: Marvel at Poland's salt mine, explore a Cold War bunker, uncover an ancient Egyptian site and probe China's mysterious Longyou Caves. (S1, ep 2) 7+ 2026-08-15 Supersize building projects revealing how the construction of a 26-kilometre subway line through Rome has unearthed some of the most important discoveries of the modern age. 7+ 2026-08-15 Stansted Crash: A look at the fate of Korean Air Cargo flight 8509. 4 died in the explosion near Stansted Airport, making it the airline's fifth accident in two-and-a-half years. 7+ 2026-08-16