Costa kicked over a couple of sods of grass. There was stone beneath, the ribbed surface of what looked like some kind of column.
“They brought in the bulldozers,” Turnhouse added. “They tore everything down. When we found it, all this area was still beneath the earth. There was an original entrance fifteen, twenty metres, by the park up there.”
“You mean it was made that way?” Peroni asked. “Underground? Why?”
She shrugged. “We don’t know. A place like this could have helped us understand. Mithraism was some kind of male cult, most popular among the military. It involved strict codes of behaviour, a series of rituals and hierarchies, with just one leader, a man who had absolute power. Apart from a few contemporary descriptions that survive, we’re speculating about the rest.”
Peroni scowled at the area around them. There were, Costa could see, what looked like the remnants of blocked-up tunnels and even a few small holes. Large enough for a child, perhaps, nothing bigger.
“So,” Peroni persisted, “this was like all that black magic stuff you still read about in the countryside from time to time?”
“No!” she replied quickly. “Mithraism was a faith. A real one. Followed very scrupulously, in secret, by thousands and thousands of people. Christianity was underground for most of three centuries before it became the dominant religion. The day that happened, the day Constantine won his victory at the Milvian Bridge in AD 312, is when everything here was destroyed the first time round. Somewhere in there,” — she pointed to what looked like a former entrance, now blocked with rubble and wire mesh to keep out intruders — “we uncovered the remains of more than a hundred men who’d been gathered together and slaughtered. By Constantine’s army. It couldn’t have been anyone else. The evidence is still there somewhere. It was one reason Giorgio felt so nervous about letting people understand the full extent of what we’d found here. There were… resonances.”
Peroni glanced at Costa. The two of them had discussed this idea already.
“If Alessio got lost, it would all have been made public anyway, wouldn’t it?” Costa asked her. “Could that have been why he brought the boy here?”
She treated the question as if it were irrelevant.
“Search me. You had fourteen years to ask that of Giorgio.”
“Then why did he come back to see you last week?” he persisted.
She actually laughed. “It was absurd. He wanted all his old files. His reports. His maps. Everything he’d worked on.”
“And?” Peroni asked.
“I threw him out! He worked for the university. Everything he produced during his employment is legally ours. I wasn’t giving it all away.”
“I imagine he didn’t like that,” Costa commented.
“That’s one trait he didn’t lose in jail,” she replied. “Giorgio always did have a temper. He was screaming at me as if I was still some timid little student of his. That I don’t take. Not from anyone.”
Judith Turnhouse hesitated. There was more, Nic realised.
“I ran off some copies of the maps he wanted. That was as far as I was willing to go. I was about to phone and tell you people about it when I read what was happening.”
She went quiet.
“When?” Peroni asked, nodding.
“This afternoon.”
“After the year-end budget?”
“Don’t patronise me.” Judith Turnhouse spoke with a slow, hard fury.
Costa was poking around at the edge of the clearing. There was a multitude of potential openings and tunnels in the ground that stretched from the fence by the narrow Roman alley, and ended in the sheer face of the hill on the other side.
“Where could a child have gone in a place like this?” he asked, almost to himself. “Why didn’t they find him?”
“I don’t know!” she exclaimed, exasperated.
“You went down there,” Peroni pointed out. “You were one of his students.”
“Yes! And that’s exactly why I don’t know. The conditions here were the worst I’ve ever encountered. Giorgio took such risks I sometimes wondered if we’d get out of the place alive. Some of the underground tunnels were so fragile you could bring down a landslide just by putting your hand against the wall. It’s a nightmare down there. There are man-made tunnels, natural fissures, drainage… Some parts link up with at least two branches of the river in ways we don’t even understand. Also, there are ways down to springs that emerge in the riverbed, too. If a child got lost in there, he could find a hundred different holes to fall down, and every one of them would kill him. Or…” — she stared at them — “someone could have thrown him down one.”
“You knew those students,” Costa stated. “Would they have done that?”
“Ludo Torchia was a twisted bastard. He could have done anything. But I still believe…”
She thought of something. Judith Turnhouse stooped and picked up one of the empty water bottles, one with a very visible bright red label.
“If you want to understand what we’re standing on here — a honeycomb no one, not even Giorgio, got round to mapping — watch this.”
The woman twisted the cap off the bottle, scooped some earth into the neck as ballast, and walked over to one of the few open fissures in the rock behind.
“This is a trick we learned when we were working here. My bet is it happens even more quickly now than it did back then. More rain. More erosion. Watch…”
She beckoned them to come close, held the plastic bottle over the hole, and let go. They heard the thing bouncing off rock, softer, softer. Then a distant splash into water. Then nothing, except the echoing soft ripple of a distant current, moving somewhere beneath them, constant.
“We thought this was a natural culvert, never part of the temple at all. There’s some kind of channel that descends, meets something else in the hill, then runs to the river. See there?”
She pointed towards the city, at an area of foaming water on the near side of the bridge before Tiber Island.
“By the weir there’s an outlet of the Cloaca Maxima, on the bend. You can just about make it out. The head itself is Claudian. There’s a modern arch around it they made when they built the road and the flood defences.”
Costa sought the gap in the line of the flood wall, almost directly by the churning waters of the weir.
“Got it,” he said.
“As you’ll see in a moment, somehow — and for the life of me I fail to see how this is possible — that little channel here works its way through several hundred metres of horizontal rock and ends up there. What we’re standing on is porous, fault-ridden stone, full of holes and hidden passages we can’t even begin to chart. If a child went down a place like that…” She sighed and looked at her watch. “So how is your eyesight? Mine’s not so great these days. I’m afraid this is the only party trick I have.”
“Very good,” Costa replied, watching the bobbing debris on the distant river like a hawk.
They waited five minutes. No red bottle appeared.
“When did you last try this?” Peroni asked. “Before Alessio disappeared? Or after?”
“I don’t remember. After, I think.”
“So it’s years? The drain probably got blocked.”
She shook her head. “No. That’s just not possible. We know when there’s a drainage problem around here. We’ve got sites that flood straightaway. There’s been nothing like that for a long time. On a day like this…” She pointed at the foam on the weir. Small white horses, lively, wild. “…without a blockage the water should be running more freely than usual. The channel’s still open here. You heard it yourself. I don’t know…”
For the first time since they met her, Judith Turnhouse looked uncertain of herself, vulnerable, capable of thinking that there might, perhaps, be something in her world that hadn’t been discovered, labelled, and filed safely away for the future.