The first few men ran past, climbing the last flight of stairs. Macro went after them. There was a brief cry of alarm, quickly cut off. As he emerged on to the roof, Macro glanced round. There was a low wall topped off with a wooden rail surrounding the roof. In one corner was the palm-leaf shade. In the opposite corner the signal brazier. There were four bolt throwers. A dull glow came from a small niche where an oil lamp stood ready to light the brazier.

‘You two!’ Macro pointed at the nearest of his men. ‘Get downstairs and seal the door. Barricade it with whatever’s to hand.’

He hurried across to the rail and stared towards the fort. A handful of torches glowed by the main gate and by their light he could see a pair of sentries standing on the gatehouse, apparently unconcerned. The dark shapes of three ships lay beached on the shore in front of the fort. There was no sign of alarm.

‘Good.’ Macro nodded to himself. Then he turned and crossed to the brazier, snatching up some of the kindling. He then carefully picked up the oil lamp and made his way down the stairs and outside. He set the lamp down and made a small pile of the kindling against the side of the tower facing the sea, and presented the flame of the oil lamp to it. The pallid yellow flicker licked the bundle of dry twigs and palm leaves. Then there was a puff of smoke as the flame caught and quickly spread through the rest of the bundle. The wall around the fire lit up with a bright yellow glow and Macro stood back and turned to look out to sea, searching until his eyes fixed on the distant shapes of the warships.

There was a shout from inside the tower and Macro looked up and saw light flickering from a small window halfway up the wall. The light quickly intensified and now the crackle of flames came to his ears.

‘What the hell?’ He hurried round to the door as the first of his men came stumbling outside.

Macro grabbed the legionary. ‘What’s going on?’

‘There’s a fire in the sentry’s quarters, sir! The oil lamp must have gone over and set light to one of the bedrolls.’

‘Fuck,’ Macro gritted his teeth. ‘We have to put it out, quick.’