The notches were cut into the cavern walls above the waterline as Salvatore had said. Elena stood in the bow playing the beam of a flashlight on them as Harry rowed the skiff slowly down the channel.

Harry worked from the center, his back to Elena, his concentration on the oars, trying to keep them silent as they lifted from the water and then dropped back in.

'Listen-' Elena clicked off the flashlight.

Harry stopped, oars raised, the boat drifting. But he heard nothing other than the soft lapping of water against the rock walls as the boat slid past.

'What was it?' Harry's voice was barely a whisper.

'I… There-'

This time he heard it. A distant rumbling, the sound reverberating off the walls. Then it stopped.

'What is it?'

'Outboard motors. Run for a few seconds, then shut off.'

'Who?'

'Whoever Edward Mooi warned us about. They're here, in the canals… trying to find us…'

Hefei, China. City of Hefei Water Filtration Plant 'A'. Still Tuesday, July 14. 6:30 p.m.

Li Wen stood back, calmly watching the people hover around the wall of gauges and meters measuring the pressure, turbidity, flow rates, and chemical levels. Why they were still standing there, he had no idea. The gauges and meters were still. The plant had been shut down completely. Nothing moved.

Zhu Yubing, governor of Anhui Province, merely stared, as did Mou Qiyan, deputy director of Anhui Province Water Conservancy and Power Department. The angry words, the accusations, had been made as the official word was given – Chao Lake had not been poisoned deliberately, by accident, by terrorists, or by anyone else; nor was pollution, caused by untreated water discharged from local farms and factories, the cause of the catastrophe; sun-fed algae, with its production of biological toxins, was. Both men had complained for years that this was a time bomb that had to be defused, a dangerous problem that had to be solved. But it never was. And now they stood in shock at this incredible horror. Putrid and deadly water pouring from the city taps like a plague before it had been shut off. The sheer numbers were beyond belief.

Chao Lake, water supply to nearly a million. In the last ten hours:

Twenty-seven thousand five hundred and eight confirmed dead.

Another fifty-five thousand seriously ill. Thousands who ingested the water in common everyday circumstances still unaccounted for. The toll in sickness and death was mounting by the minute. And little could be done, even by Chinese Army disaster teams, except take away the dead. And wait and count. The same as Li Wen watched them do now.

The only sound was the lap of water against the rock. That and Danny's regular breathing. Elena stood frozen in the bow, while Harry let the skiff drift with the current, holding it just off the rock with his hands so it wouldn't scrape. Trying to keep it silent.

The dark was infinite. Impenetrable. Harry knew Elena's thoughts were the same as his. Finally Harry's whisper broke the silence. 'Put your hand over the front of the flashlight. Let as little of the beam out as possible. Keep it high on the wall. If you hear anything, shut it off.'

Harry waited and then the dark was cut by a narrow wand of light that searched the granite wall above them. For a long moment it inched over the ancient stone, looking for the directional markers but finding nothing.

'Mr Addison-' Elena's whisper was abrupt and for the first time Harry heard fear in her voice.

'Keep the light moving.'

Immediately, Harry pushed the skiff back from the wall, then eased the oars into the water and pulled gently. The craft moved forward against a barely perceptible current.

Elena could feel the perspiration on the palms of her hands as she watched the sliver of light play fruitlessly over the rock.

Harry watched it, too, trying not to think that they had drifted too far in the darkness and were moving deeper into the labyrinth. Suddenly Elena's light passed over three notches cut in the stone, and he heard her stifle a cry.

'Okay, we're still okay,' he whispered.

Twenty feet passed, then thirty. Then three more notches.

'Turn the light down the channel.'

Elena did. The rocky cavern went straight for as far as they could see.

'Put it out.'

Immediately Elena snapped the flashlight off, then turned forward and peered into the dark in front of them, praying to see a dot of light that would mean the end of the canal and the way out to the lake. But she saw only blackness. Felt only the same cool damp of the air. Heard the light sound of the oars as Harry moved them forward.

Absently, she crossed herself. This was more of God's testing. But this time it wasn't about men or lust but about her own courage, her ability to persist under the most unbearable of situations while at the same time remaining strong and true to the patient in her charge.

'Yea, though I walk through the valley of the shadow of death,' she began to chant under her breath, 'I will fear no-'

'Sister Elena-' Salvatore's voice suddenly echoed out of nowhere.

Elena started. Harry froze where he was, oars out of the water, the skiff drifting forward.

'Salvatore,' Elena whispered.

'Sister Elena-' Salvatore's voice came again. 'It's all right,' he called in Italian. 'I have the boat. Whoever was here is gone.'

There was a distant whine and then the sound of motors. The white of Elena's eyes flashed in the dark as she turned toward Harry, translating what Salvatore had said.

'Sister Elena, where are you?'

Instantly Harry pulled in the oars, then grabbed at the passing wall of rock, slowing the skiff by hand. Stopping it. The sound of the engines was suddenly louder. The boat was coming up the channel toward them.

Thomas Kind held the edge of the razor against Salvatore's throat as the motorboat moved slowly forward, the sound of the outboards echoing off the cavern walls. Behind them, Marta lay on the deck between the cockpit and the motors, blood still oozing from a tiny hole between her eyes.

Salvatore turned slightly to look at Thomas Kind. The right side of the blond man's face was raked with blood and torn skin where Marta had clawed him when he'd caught them, just as they'd reached the elevator cage. The fight had been short and quick. But she had done damage, and for that alone Salvatore Belsito was extraordinarily proud.

Yet Salvatore was not like his wife. Did not have her bravery or rage. It had been difficult enough for him to do what he had in lying to the police when they had twice invaded Villa Lorenzi. Difficult enough just to come to the grotto to care for the fugitive priest while the nun went in search of his brother. Salvatore Belsito was Villa Lorenzi's chief gardener, a gentle man who loved his wife and only cared about making things grow. Eros Barbu had given them both a home and jobs for as long as they cared to have them. For that he owed him a great deal. But not his life.

'Once more,' Thomas Kind urged.

Salvatore hesitated, then again called out Elena's name.

The stab of Salvatore's call resounded off the granite walls like an effect in a thrill chamber. It was much louder, much closer than before. Abruptly it was overridden by the throaty rumble of the outboards as they picked up speed.

'Go right,' Elena said behind him, the slim beam of her light following the marks on stone as they reached a turn where the tunnel veered sharply right, nearly angling back on itself.

Harry pulled hard on the right oar, cutting the corner too tightly. As he did, the left oar caught on the cavern wall and was nearly jerked out of his hand. Cursing under his breath, he recovered, felt the left oar touch water, and they were around.