The sun went down like a tin duck at a shooting gallery. Night stretched itself over the eastern Arabian desert, the light from a clear full moon creating a finely filigreed landscape of silver and black.

At an altitude of 1,000 feet a twin-engine Griffon-3 transporter plane released a stick of paratroopers in alternating door technique, ten on either side. Canopies flared immediately. The twenty men turned into the wind and dropped to the desert floor as silently as thistle seeds, each making a perfect five-point landing. Within minutes their chutes were buried and they were jogging towards Mount Hor and the dead city that nestled in its shadow, Petra.

They filed through the Siq, Petra's eastern gateway, a sheer-sided gorge hacked out by a long-ago earthquake and smoothed by water erosion. In places it was so narrow they could barely walk two abreast. Above, the sky was a distant strip of starshine, a glittering river meandering between black banks. The paratroopers moved carefully, wide-eyed in the near-total darkness of the gorge. The path sloped steeply, uneven underfoot. Each man held his ibis-headed ba lance at the ready, reassured by the warmth he could feel through the handgrips, the charge of divine essence that glowed within the weapon.

The Siq opened out onto a valley. Directly ahead lay the rendezvous point, a Romanesque temple hewn out of the face of a sandstone cliff and known as Al Khazneh, ''the Treasury''. Its colonnaded and porticoed entrance towered before the soldiers. Essentially a decorated cave mouth, it exuded a dusty silence, the breath of the ancient darkness within.

On the steps of the Treasury, Lieutenant David Westwynter lowered his lance and checked his watch. Precisely 8pm.

''Bang on time,'' he muttered. ''At least, we are.''