Or are the final blitherings of a madman, he told himself.

Still, a part of him was – perhaps – a bit afraid. He had never been superstitious. Not exactly. However, he had seen things that had given him pause over the years. He had never expected lost Atlantis to be found again, and especially not to have walked through part of those fabled lands himself.

But he had.

‘So tell me about the cistern,’ Cleena invited.

Ahead of Lourds, Olympia blew out an angry breath and cursed.

Lourds didn’t mind.

‘Today, the cistern is more commonly known as the Basilica Cistern, which was the name first given to it.’ He spoke quietly but his voice still echoed. ‘The Turks called it Yerebatan Sarayi, which means Sunken Palace, and Yerebatan Sarnici, which means Sunken Cistern. In fact, we shouldn’t be far from it. The cistern was constructed near the Hagia Sophia.’

‘Since the cistern’s sunken, I suppose that means it’s underground.’

Lourds negotiated a particularly narrow passage then continued, ‘Exactly. And it ties back to the construction of the church. It was built underneath the Stoa Basilica, a public square everyone used. The emperor allotted the water usage during times of drought, but otherwise people were free to come and go and use as much as they needed.’

‘I guess during times of drought though, the emperor wasn’t so generous.’

‘No, he wasn’t.’

‘Having the cistern so close to the castle meant the emperor’s guards could easily defend it.’

‘Yes.’

‘Constantine sold the idea of the cistern to the people by saying it was for the common good, then took it back if he needed it. Close placement to the castle just made it easier.’

‘I suppose so,’ Lourds said. ‘But it also made the cistern more defensible when the city was under siege. I think that was the original concept. I don’t know that Constantine ever kept the citizens from the water, but the city was sacked and besieged on more than one occasion.’ He did, however, think the comment was indicative of her particular mind set.

‘How big is the cistern?’

‘It’s the largest in Istanbul. As I said, Constantine started the cistern, but Justinian enlarged it after the Nika Riots of 532 AD. It’s almost five hundred feet long, a little over two hundred feet wide and thirty feet deep.’

‘Big swimming pool,’ Cleena commented.

‘When it was full, the cistern held almost three million cubic feet of water. There were also over three hundred marble columns supporting the cistern’s ceiling. It looks like rows of picket fencing. Interestingly, there are two Medusa heads in the cistern.’

‘Medusa heads? As in the snake-haired woman whose glance turns people to stone?’

‘Yes,’ Lourds agreed, ‘that Medusa.’

‘Sounds kind of strange for a Christian emperor to put something like that in his cistern, don’t you think?’

‘There is some conjecture regarding the placement of the Medusa heads. One stands upside down, and the other lies on its side. Both support pillars. Some historians believe that Constantine simply availed himself of whatever materials there were to build the cistern. The heads were thought to have been salvaged from a Roman building.’

Olympia stopped so suddenly that Lourds ran into her.

‘If you’d been paying attention,’ Olympia said, ‘that wouldn’t have happened.’

‘My humblest apologies.’ Lourds didn’t put his heart into the effort. He knew she was primarily irritated by the attention he was paying to Cleena. ‘Why did we stop?’

‘Because we’re here.’ Joachim shone his flashlight over the wall to his right. Ahead of him, the passageway split into a Y and continued into double-barrelled darkness.

Lourds played his light over both tunnels but saw no discernible difference between them. ‘Which way?’

‘Here.’ Joachim leaned into the wall and pressed a series of stones.

Faint clicks barely reached Lourds’ ears. He placed his hand against the wall and felt the vibrations as Joachim shoved back a section large enough for them to pass through.

‘Come on.’ Joachim disappeared into the hole in the wall.

On the other side of the wall, Lourds pointed the flashlight ahead of him, then behind. There was only one way to go: forward. The tunnel dead-ended behind them. This tunnel was narrower than the first tunnel. He had to turn sideways to go along it.

‘This way was made for smaller men,’ Joachim said.

‘Obviously.’ Lourds held his hat in one hand over his heart. His backpack slid along the rough stone, catching every now and again. Against his forearm, the stones were worn smooth. He couldn’t help wondering how many people had traversed this tunnel since its construction. He also imagined the stories they would’ve had to tell.

‘No one has been here in a long time,’ Joachim said. ‘I’ve only been here three times my whole life.’

‘Why?’

‘Because this is a holy place, and because the scroll is not here.’

Lourds knew the last was intended as a goad but he ignored it. He hadn’t told any of them that the Joy Scroll was within the room. He just hoped he was right concerning his other suspicion.

‘Who knows about this place?’

The grade in the tunnel angled more steeply downwards. Lourds stepped carefully now as he descended. He thought he felt impressions that might once have been steps carved into the solid stone. The centre of the passageway was bowed slightly, as it was more worn in the middle.

‘Everyone in the Brotherhood.’

‘Do they come here?’

‘No one is allowed here. Until today, no woman has ever been in this passageway.’

‘Not even Olympia?’

‘Not even my sister.’

‘Joachim was even better at keeping secrets than I expected,’ Olympia said. ‘I didn’t know he was part of the Brotherhood until a couple of months ago.’

‘How are the brothers chosen for the order?’ Lourds asked.

‘Usually it passes from father to son,’ Joachim answered. ‘Occasionally a nephew must be brought in, or an older monk may pass his knowledge on to a grandson.’

‘Your father?’

‘Yes.’

‘Another big secret keeper,’ Olympia said.

‘Our father began telling me about the Brotherhood when I was just a child,’ Joachim said. ‘I loved the stories and the idea of being part of something so secret and so important. As I grew older, I also grew more serious about my responsibilities.’ He paused. ‘The hardest part was occasionally losing faith and thinking that the scroll I had sworn to protect was already gone.’

‘What if we find out it is?’

Joachim halted in front of a bare wall. His flashlight beam bounced off the stones and highlighted his features. He looked grim.

‘As I told you before, Professor Lourds, as long as the world is safe, we are not too late. The Joy Scroll still exists. It is out there and we have to find it.’

Lourds shone his beam over the blank wall. He searched for signs of crevices or cracks, but there were none that he could see.

‘Another door, I suppose?’ he asked.

‘Not exactly.’ Joachim knelt and pressed against certain stones set into the floor.

In the next moment, a section of the floor receded a few inches. Joachim hooked his fingers into the gap and pulled. Stone ground as the hidden door slid out of the way.

The glare of the gathered flashlights revealed the stone steps going downwards. Joachim led the way.