There was movement outside, and the two soldiers came to attention as Sura and a well-dressed Indonesian officer with a supercilious air came in. Seeing the rage in Mia’s eyes, Nash knew he had a new enemy.

‘This is your illustrious cave diver?’ Alatas chuckled sceptically. ‘He looks more like a drowned rat.’

‘The rain is coming, Kapten,’ Sura said curtly. ‘Mr Nash, you have your friends as promised. I want you inside that submarine, planning your strategy should diving become necessary. Be ready in an hour.’

A distant roll of thunder underlined her instructions and, with a glance at Alatas, she led him out of the tent. The two soldiers took up position outside and another chopper flew overhead.

Nash stared at Frank and Mia. ‘Why didn’t they just fly us up here?’

Mia explained these were not Suyanto’s men.

‘You think Sura is double-crossing her father?’

‘I wouldn’t put it past her,’ muttered Douglas.

With an hour to spare, they filled in the gaps. For Mia, the realisation that the Ford Missions were built on Axis gold was painful to reconcile with their purpose. Nash tried to put her at ease.

‘From the transcripts I read, Paul Ford’s father was no Nazi. So maybe it was about making amends?’

‘But wouldn’t it have been better to just come clean? I mean, is it really charity when it’s someone else’s money?’ Her voice caught in her throat. ‘They burned the mission when we left. What a tragic and stupid waste.’

Nash told them about finding the sub, and what he knew of the Hoosenbeck system.

‘There’s a flooded exit passage at the bottom of the sinkhole. Last night I went in there looking for answers, but I didn’t find any.’

Mia took his hand. ‘They’re not going to let us go, are they?’

‘Any ideas, Frank?’

The old pilot lowered his voice. ‘The border is only ten klicks away. If we snatch one of these helicopters, I could fly us to Tabubil in less than half an hour.’

Nash cleared his throat. ‘Are you really in a fit state to fly?’

‘Help me up.’

Together they got Douglas into a sitting position and, after checking no one was watching outside, pulled him to his feet. He swayed, but stood on his own, before taking a tentative couple of steps and turning around.

‘Reckon I can make ten klicks.’ He chuckled at Mia’s amazement. ‘Maybe we should find that old witch doctor and cut a patent?’

Nash grinned. ‘What’s to stop them following us over the border, Frank?’

Douglas let Mia ease him down before answering.

‘Tabulil is the site of the Ok Tedi mine, one of PNG’s richest. I can’t see them coming in after us with a few hundred foreign mining workers watching on, can you?’