‘The water flows down through that closed channel just below the parapet,’ he told Marcus and Serpentius, whom he had asked to accompany him. ‘You can see that it runs above ground for about two hundred paces down the hill before it disappears among the houses. I’ve had a look and there’s no set pattern to its course. Sometimes it’s buried beneath the street and runs under the buildings, sometimes it’s a mini-aqueduct and passes over or even through them. It depends on the terrain. That’s why we have to follow it. The only way we’ll know if the water’s still running is to check at one of the inspection hatches.’ He showed them a key Honorius had given him to help lift the big capping stones. ‘So we’ll inspect at regular intervals when we get the opportunity. There has to be a fair chance that the channel has collapsed somewhere along the line, so it may be quite close. But if it isn’t we’ll follow it to the end.’
‘What happens when we get there?’ Serpentius asked. ‘Maybe it’s time to be Praetorians again?’
Valerius shook his head at the Spaniard’s sudden enthusiasm for what he had once despised. ‘We have no idea what we’ll find. If it’s what I think it is, it will be hidden in some kind of building, but probably not a public one. We may have to knock on doors or we may have to go through windows. You wouldn’t want to do that in armour.’
Marcus grinned. ‘I doubt he’d mind one way or the other. It’s never stopped him before.’
‘Honorius will have men here if, for any reason, we need the supply cut off. If we have time, we’ll send someone back with word, but if not we use the old legionary signal system.’ Valerius pulled a polished metal disc from the sleeve of his tunic and raised it in the air so that it caught the sun. ‘Very simple. One flash for off, two flashes to restore the supply. The people here will give one flash to confirm. Understand?’ They nodded. ‘The tower is in direct line of sight from the south slope of the Viminal Hill, so that is where we’ll make the signal. The two water men in the tower have been told to watch for it and they’ve rigged up a new mechanism to open and close the gate.’
With a bow to the commissioner they set off down the track that ran alongside the conduit. This was a mere side line of Old Anio, but it had been built to last, with arches of mortared stone ten feet tall carrying a single channel two and a half feet wide. It was also in remarkably good repair, with signs of recent masonry work that made Valerius ever more certain they were on the right track. They found it simple to follow the undeviating course down the slope of the hill, but then their problems started. Once among the houses the aqueduct maintained its line, but sometimes between the apartment blocks and sometimes directly through them, where the builders had made the water channel part of the structure itself. At last they came to a halt.
‘It’s gone,’ the Spaniard said, looking at the building in front of them as if he expected the aqueduct to make a surprise appearance. ‘It goes in the back, but it doesn’t come out of the front. Maybe this is it?’
Valerius studied the insula. It was one of the smaller blocks in the area. ‘I suppose it’s possible, but it doesn’t feel right.’ He walked to the rear of the building, where the aqueduct undoubtedly entered at first floor level, and returned to the front where there was no sign it existed. They were about fifty paces from the Vicus Patricius and he followed what he thought was the channel’s line out on to the street until he found what he was looking for. He took the key Honorius had given him and placed it in the hole in the stone block which covered the inspection shaft. It was heavy, but even one-handed he could lift it far enough to see the water flowing beneath.
For the next two hundred paces they moved from shaft to shaft, scrabbling on the ground among the stinking open sewers, random dog shit and rotting fruit for the next one, until, without warning, the Glabrian link took to the air again and marched in arched leaps to the lower slopes of the Viminal where it disappeared once more — directly into the hill.
‘You think these people are moles?’ Marcus asked.
Valerius didn’t reply. He led them through the alleys at the base of the hill and round to where Honorius had told him the Thermae Glabrianae, once the pride of one of Rome’s greatest families, had stood. They were on the far edge of the Subura now, on a slight rise where an infrequent, unlikely breeze ghosted its way among the houses to take the jagged edge off the intense heat. Here the apartment blocks were larger and an occasional sumptuous villa clung to the edge of the hill. Valerius turned to study them and his eye settled on one villa in particular.
‘That’s it,’ he said. ‘That’s the one.’
‘Watch out!’ Marcus made the gladiator’s secret sign that warned of danger to the rear. Valerius forced himself not to look round. ‘The place is crawling with Praetorians and that bastard Rodan is nosing around looking for trouble.’
‘Has he seen us?’
‘I don’t think so.’
‘Then we go back the way we came. Be natural. Don’t make a fuss.’
A few minutes later they sat together in the shadow of one of the aqueduct’s arches on the opposite side of the hill. ‘How were they waiting for us?’ Serpentius demanded.
‘They weren’t waiting for us. They’re looking for Petrus. Rodan knows what we know and he’ll have every rathole in and out of this district sealed tighter than the stopper in a wineskin. We can’t get in and the Christians can’t get out. He’ll scoop them up like fish in a net and then they’ll go the same way as Sulla and Lucina.’
‘Does it matter if Rodan gets to Petrus and a few of these Christians burn?’ Marcus asked. ‘The Emperor can’t blame you just because the Blacks got there first.’
Valerius said bitterly, ‘It matters to me.’ He told them about his father and Olivia.
‘Well, you were right,’ Marcus said. ‘We might get in but we’d never get back out with an old man and a sick woman. They have the house watched from every corner. Anyone who tries to leave will be picked up the minute they stick their nose out of the door.’
Valerius looked up the hill past where the channel disappeared into the rock. ‘What if I could get in? Would it be possible to create enough of a diversion to allow me to get my father and Olivia away?’
‘We could try,’ the scarred gladiator said. ‘But I don’t see how you can get in unnoticed. The place is guarded as tight as a mouse’s arse-hole.’
‘There must be another way.’ Valerius began to climb the hill.
Minutes later they lay flat on the ground looking over the edge of the hill above the villa which had caught Valerius’s attention. The Viminal was occupied mainly by a patchwork of apartments and small allotments, but here, where the hill was steepest and the soil thin and worthless, it had been left clear. The slope fell away sharply, almost a cliff, and the roof of the building was probably fifty feet below them.
‘Well, that’s that,’ Marcus said. ‘If you try to get down there, you’ll be lucky if you only break your legs.’
Valerius had studied the face with equal care and he realized that Marcus was right. This was no conveniently fractured Dacian rock; it was weathered almost as smooth as glass. What was more, it was visible from the streets below where Rodan and his men waited. There had to be another route.
They searched the edge of the hill for an alternative and Valerius was beginning to despair when he noticed something unnatural in the dried yellow grass. It took a few moments before he recognized it. He was standing over yet another of the inspection shafts.
He walked back to the far side of the hill and did his best to work out the course of the aqueduct. When he was satisfied, he stood for a moment with his head bowed. He tried to visualize the interior of the channel below his feet. Could it be done? When he looked up, Marcus saw the same look in his friend’s eyes as he had seen in gladiators making their final appearance in the arena: a confused mix of fear, resolve, certainty and confusion. Valerius handed Marcus the polished bronze disc and reached down to place the key in the capstone. ‘Signal the water tower to cut the supply.’