The noise of the shooting below was tinny and distant; it sounded like nothing worse than a fireworks display. Here by the lake it was calm and peaceful. The sun sparkled on the water. The mountain peaks were honey-coloured against the perfect clear blue of the sky. But James knew that somewhere up here was a killer, intent on turning this idyllic postcard scene into a vision of hell.

‘Is he here?’ said Amy.

‘I don’t know,’ said James. ‘Maybe I was wrong.’

He scanned the lake. Along the left-hand side was a small run of low buildings. There was no reason why Zoltan would have gone there, but where was he?

‘What did your cousin say exactly?’ said Amy.

‘He thought that that long overhanging rock over there was unstable,’ he said.

‘So he’d have headed for that, then,’ said Amy.

‘I suppose so,’ said James. ‘Let’s go and look.’

Ugo’s motor launch was moored next to the big, ungainly seaplane at the jetty. James ran out and jumped into it.

‘Do you know how to work one of these things?’ he said.

‘Yes,’ said Amy excitedly as she climbed aboard and cast off the rope. ‘I’ve spent half my life on boats.’

She busied herself with the motor, glad to be doing something to take her mind off the danger they were in and the terrible violence they had witnessed.

Soon the motor launch was speeding out across the water, churning up its glassy surface and disturbing the fragile peace. Amy was steering and James pointed her towards the right-hand side of the lake. Once they were near the overhanging shelf of rock they slowed down, and cruised slowly along, keeping their eyes fixed on the coast, looking for anything that might give them some idea of where Zoltan was.

And then James saw the black mouth of a cave.

‘Over there,’ he said, and Amy moved the boat closer. They saw that the entrance had been enlarged and was shored up around the edges to make it safe to enter.

Amy manoeuvred the launch into the cave and they found themselves in a short tunnel lit by a string of bulbs in the ceiling. They followed the lights around a corner into a small, gloomy cavern. It was cold in here and the air felt damp. Water ran down the walls and dripped from the roof, and everything was coated in green slime.

James quickly took in the details. There was a small dock for mooring boats, and a rotting wooden platform built on concrete piles with an iron staircase leading up from it through a fissure in the rock. There was a stack of mouldering barrels on the platform and as James tied up the boat Zoltan stepped out from behind it. His face was covered with a film of sweat and his eyes were mad with fever and burning red.