Another lengthy pause, then Sandra took out a phone and dialled. ‘Dougie, are you busy right now? Okay, can you do me a huge favour? I’m at the airport, with four other people. Can you pick us up and fly us to the rock? Yeah, it’s serious – I wouldn’t ask otherwise. Okay, thanks.’ She looked back at Nina. ‘A mate of mine owns a helicopter for tourist flights around the rock. He’ll take us there so we can search from the air.’

‘Thank you,’ Nina replied.

Eddie and Macy came back. ‘Oh great,’ grumbled the Yorkshireman. ‘Another helicopter.’

‘You don’t like helicopters?’ asked Sandra.

‘Our last flight didn’t end very well,’ said Cheng.

‘Hopefully this one’ll be better. Come on,’ she said, leading them through the terminal.

The promised helicopter arrived fifteen minutes later, a Jet Ranger painted in the colours of the Australian flag. Sandra ushered everyone else into the cabin’s rear, then took the co-pilot’s seat. The chopper quickly took off and headed south-east. ‘All right,’ she said once they had all donned headphones, ‘Rosie went looking for this plane somewhere north-east of the rock. It’s off the tourist flight path, so even if there was something there, probably nobody would have noticed it.’

‘Why not?’ Cheng asked.

The pilot, a middle-aged man with deeply tanned and wrinkled skin, pointed ahead with a chuckle. ‘They’d be looking at that, mate!’ All eyes went to the great red rock of Uluru, rising with almost startling suddenness from the desert plain. Even from a distance it dominated the landscape, a towering sandstone iceberg in an empty orange sea.

‘Wow,’ said Nina. ‘Now that is impressive.’

Eddie nodded. ‘That bloke Ayer must’ve had an ego even bigger than the rock to name it after himself. How big is it?’

‘Over three and a half kilometres long and almost two and a half at its widest,’ Sandra announced. ‘Three hundred and forty-eight metres tall at the highest point.’

‘How far underground does it go?’ Nina asked thoughtfully.

‘Underground? I don’t actually know. Three or four kilometres, I think, although some people reckon it could be more. Why?’

‘What these people are after might be inside the rock.’

She shook her head. ‘You can’t get inside. There are caves, sure, but they’ve all been explored, and none of them are very deep. If there was anything there, the Aboriginals – the Aboriginal people,’ she corrected, with a patronising smile at Macy, ‘would have found them.’

‘The entrance might have been hidden.’

‘By who?’