"At the end of a winding dirt road, the team dismounted from their Humvees and surveyed the rocky valley. 'Afghanistan’s in the thirteenth century, but this place was Paleozoic,' Rory told me later. 'If a T. rex walked out from behind a hill and growled at us, it wouldn’t’ve fazed me at all.' They were there for about ten minutes when SECFOR Staff Sergeant Dwayne Koons spotted 'dismounts'—Afghans on foot—watching them from some nearby rocks. Rory shrugged it off: 'Watching Americans is like the Afghan national pastime.' But these guys bugged Koons and they bugged Mitchell, too. 'It sparked our spider senses,' Mitchell said. Koons told Rory, 'We have to go right now.'

The team was expecting air support on the way back because, as Mitchell told me, 'the enemy is known to hit you on the exfil'—to attack a mission as it heads for home. But when they returned to their Humvees, the men received a message: the support choppers weren’t coming. Their sense of foreboding grew.

They headed back along the winding dirt road. A wall of mountains rose to the left of them. A sheer drop-off fell away to the right. Mitchell and Rory were in the second vehicle, separated from the lead Humvee by about 20 meters. They heard the first explosion go off right behind them.

'The cry went out over the radio,' Mitchell said,  ‘We’re taking fire!’ ”

Read Five Days at the End of the World, by Andrew Klavan.