'Keep still!' Cato warned him.

'What?' Macro's head rose. 'What's going on then?'

The snake hissed again, louder, and near the top of its body it began to swell out. The sinewy coils beneath writhed momentarily as it edged forward.

'Shit,' Macro whispered. 'We're in trouble, lad. What do we do?'

Cato stared at the snake. It was close enough now to make out the individual bumps of its scales, and the beady gleam in one of its eyes. A sudden flicker indicated where its mouth was as the cobra's head towered over the two men.

'Just… keep… still,' Cato whispered.

'Right.'

Cato had seen some snake charmers in the market at Alexandria and knew how fast the serpents could strike. There was no chance of jumping up and dashing past it towards the swords. If either of them tried, they were dead. He reached his left hand slowly towards his tunic, lying rumpled beside the bedroll. His fingers stole across the earth towards the cloth and closed round a fold.

'Macro, I'm going to try and distract it. When I make a move you go for the swords. All right?'

'What kind of distraction?'

'Doesn't matter, just be ready. On three.'

The snake was unsettled by the noises and hissed again, still louder, and the head leaned back, ready to strike.

Cato moistened his lips and spoke softly. 'One… two… three!'

He whipped up the tunic and jumped to his feet, swinging the tunic waist high through the air towards the snake. The cobra lunged at once, whacking into the cloth before it reversed direction and hissed again. Macro had clambered up and taken a step towards the tent post when the snake slithered round and lunged at him. He jumped back on to his bedroll.

'Fuck, that was close.'

'I'll try again,' said Cato. He wrapped some of the tunic about his fist and tentatively held the rest out towards the snake. At once it turned its head back towards him, its eyes burning like rubies. Cato moved the tunic to the right and shook it. The snake struck again and at the same time Cato jerked the cloth back. The fangs, caught in the thick strands of wool, came with it and Cato gave a terrified cry as the body of the snake came towards him. He threw the tunic over the cobra's head and with his spare hand he grabbed at the neck, just below the hood. The snake's skin was dry and rough and the coils writhed wildly as Cato struggled to keep his grip and at the same time wrap the tunic about its head with his other hand.

Macro leaped forward, reached the tent post and snatched out his blade. He turned and hacked at the wriggling body and struck the ground instead.

'Macro!' Cato shouted as the head thrashed about inside the tunic. 'Just kill the bastard!'

Macro hacked again, cutting into the middle of the cobra's body. He cut again, this time severing it. Half the coils fell back and flopped about on the ground and Macro hurriedly kicked them to one side. The other half seemed to grow even more wild and Cato hurled it as hard as he could towards the back of the tent where it hit the goatskin with a soft thud and dropped to the ground, writhing frantically, but unable to move from the spot as it bled out.

Cato's heart was beating wildly, his chest felt cold and clammy and he trembled. He turned to Macro and saw that his friend was just as shaken. Macro licked his lips and stared at the dying snake as he spoke in a low, earnest tone. 'I am really beginning to hate this province…'

'You're the one in charge of the watch, right?' Macro glared at the optio as the latter quickly rose from amongst the men sitting around the fire.

'Yes, sir.' The young soldier nodded.

'Then you're responsible for this getting into our bloody tent.' Macro shook out the tunic and the two lengths of the cobra's body flopped on to the ground. The optio instinctively took a step back and his face wrinkled in nervous disgust. There were surprised murmurs from the other men as they craned their necks and saw the dead snake.

Macro turned and pointed towards the tent. 'The prefect is inside. There is supposed to be a guard patrolling outside the tent to ensure nothing happens to him, right? No enemies, or other threats, get past. I mean that's standard regulation, even here in Egypt.'

'Yes, sir.'

'So where is the sentry?' Macro made a show of looking around and giving up and raising his hands. 'Well?'

'I'm sorry, sir.' The optio swallowed. 'I had a man either end of the camp. I didn't think it would be necessary to post any more than that.'

'Two men?' Macro shook his head. 'The province is in a state of war, and before you say it, I don't care how far away the Nubians are. That's no excuse for sloppy watch-keeping. Let me guess. You're with the Twenty-Second Legion?'

The optio nodded.

'Oh great…' Macro took a pace closer and held his finger an inch from the optio's face. 'I want a proper watch posted every night. It is your duty to protect the camp and protect your officers and you have fucked up, my son. The fact is, either the prefect or myself or even both of us could have been killed and the fault would be yours.'

'But sir. Even if there had been a sentry, the snake could have got into the tent.'

'Shut it! You know what your duty is. I suggest you stick to it, or I'll be disturbing your night by kicking your arse so hard your teeth will fall out.' Macro took a step back, and prodded the snake's body with his boot. 'I'll leave you to get rid of this.'

He was about to return to the tent when the captain of their barge squatted down by the snake and shook his head. 'They don't usually give us any trouble when we camp. Your tent must be pitched near one of their nests.'

'You mean there could be more of them nearby?' Macro fumed.

'No. They're solitary creatures. Unless their young are hatching, of course.'

'Well, thanks for that. I'm bound to get a good night's sleep now, aren't I?' He turned back to the optio. 'Make that two sentries outside the tent.'

'Yes, sir.'

Macro turned and marched back to the tent and pulled the flap shut behind him. He tossed the tunic back to Cato as he crossed to his bedroll and slumped down. 'Bloody optio's from the Twenty-Second. Seems like you were right to be worried about 'em.'

Cato was sitting cross-legged on his bedroll, deep in thought. He shook his head and glanced round. 'Sorry?'

'I said you were right about the Twenty-Second being a bit slack.'

'Oh, yes.'

'Hello, Cato.' Macro waved his hand. 'Still with us?'

'Just thinking.' Cato ran a hand through his hair. 'About the snake. If there's one thing I really can't stand, it's snakes.'

'Why so particular? They're just like everything else in this province: crocodiles, mosquitoes and snakes – never content unless they're sinking their bloody jaws into someone. Fuck 'em. I'm going to try to get back to sleep.' He glanced over at Cato and continued in a more gentle tone. 'So should you. Best get as much rest as you can before we reach Diospolis Magna.'

'Yes, you're right.' Cato eased himself down and lay still, staring up at the roof of the tent. After a while he shut his eyes and lay there listening intently to every sound of the night. Although Macro lay still and silent on his side, he did not snore and Cato realised that his friend's mind was as troubled as his own.

Macro blinked his eyes open and for a moment frowned. The last thing he remembered was being unable to get to sleep, and lying still for what seemed like hours. Well, sleep had come to him in the end, he mused. Dawn was breaking outside and a shaft of light pierced the tent through the open flap. Macro turned over and saw that Cato's bedroll was empty.

He sat up and stretched his arms, yawning widely before smacking his lips. Rising to his feet, Macro saw a dark dry patch in the light-coloured soil in front of the tent post and immediately recalled the scene the previous night when he had cleaved the cobra in two, and pursed his lips sourly. Emerging from the tent, Macro saw his friend sitting on a palm log a short distance away. He was staring out across the misty river, the stopper from an amphora in his hands. A short distance away lay the remains of a broken amphora.