Now the terrain changed again, their route taking them up and up from the low-lying desert region onto higher ground that rose so sharply upward that the gaining altitude made their ears pop and crackle. From here they faced having to cross an expanse of escarpment and mountain where constricting rocky passes offered the only way through. Twice they found themselves unable to go any further and forced to turn back in search of a usable route that didn’t detour too widely from their course, adding long miles and hours to their journey. Just when they thought they’d found a relatively easy passage through the crags that loomed either side of them, they lumbered through a tight gap between two enormous rocks to find the ground to one side had sheared off completely during some long-ago landslide or earthquake, leaving a vertiginous two-hundred-foot chasm into a rubble-littered valley way below to their right, a more than vertical granite wall looming high overhead to their left and the only avenue between the two a twisting, rutted boulder-strewn ledge forming a path that at its broadest was only a couple of inches wider than the wheelbases of the vehicles.

By the time they realised their potentially fatal mistake, it was already too late to turn back. Where a narrower Land Rover would have got through without too much worry, the massively squat, crablike Humvee was so wide that its outer wheels pattered and scrabbled dangerously close to the edge of the drop, an experience that was made even more disquieting by the sidewise cant of the path that sometimes tipped them over at an alarming angle, so that the passengers on the right could peer straight down from their windows at the valley floor two hundred feet below, a sight guaranteed to make the bravest soul recoil with a shudder. The truck was a foot wider still, and in the narrower stretches its three outer tyres were overhanging the brink by more than half their width, dislodging little avalanches of loose dirt and stone as its huge wheels rolled along.

One tiny slip, the minutest error of judgement on the part of either driver, or a weak section of ground that might give away under their combined seven-plus tons, and either or both vehicles wouldn’t stop tumbling through space until they and their occupants were pulverised on the rocks far below.