A squad of six guards approached from the gatehouse and Macro’s hand slid down to the handle of his sword. He drew it a short distance from the scabbard, before Cato pressed the pommel back down.

‘Macro, that’s not going to help. Please don’t.We can’t afford to cause any trouble.’

‘Bollocks.’

‘This won’t help us to take Bannus prisoner, and return Yusef to his mother.’

Macro turned from Cato to the approaching guards, and then back to Cato again with a deep sigh of resentment and frustration. ‘All right then.’

The guards halted in front of the table and their leader approached the two Romans warily. He gestured towards their swords and Cato and Macro reluctantly drew them and handed them over.Then he indicated the entrance to the siq.

Cato turned to Symeon. ‘Where are they taking us?’

‘To the cells under the royal palace. Don’t worry, I’ll do what I can to get you out of there as soon as possible.’

‘That would be nice,’ Macro said coldly. ‘If it’s not too much trouble.’

The leader of the guards spoke to them, more insistently this time, and thrust his finger towards the siq. Cato stepped into the middle of the group of guards, and after a moment’s hesitation Macro followed him and they marched away. Once they had passed through the gate the rock faces closed in on both sides so that in places only a few men could stand abreast. Overhead the cliffs blocked out all but a thin sliver of open sky, and in places an overhang threw the passage into dim shadow. The route was paved and a small water channel ran alongside to prevent flooding. Those ahead of the small party had to squeeze to one side to permit them to pass as the guards and their prisoners made their way along the winding path into the city.

‘You can see why Pompey was never able to bring the Nabataeans to heel,’ Cato said quietly. ‘If this is the only way into Petra then a small force could hold an army at bay for ever.’

‘There has to be another way in,’ Macro replied. ‘A path through the mountains, or at least something scaleable. Surely?’

‘Maybe not. How else could Nabataea have resisted every conqueror passing through the region?’ Cato looked up at the cliffs in wonder. ‘It’s a miracle that anyone ever found this entrance in the first place.’

They turned a corner and ahead of them a narrow fissure of light split the cliffs from top to bottom. A short distance beyond the opening was an enormous structure, a temple, built from massive columns. Only when they got closer did Cato realise this was no construction, but had been carved from solid rock.