A white-hot rage ignited within him and Nash found himself bellowing, ‘You don’t know shit! You have no fucking idea about me or her, so shut your fucking mouth!’

Satisfied she’d drawn blood, Sura nodded calmly. ‘There is one key difference between you and me. While I am true to myself, you have allowed conscience to distort who you are. Guilt has weakened the courage of your convictions. That is why you are afraid, and I am not.’

A thudding of boots saved Nash from replying. Boerman arrived, festooned with rope, his big chest heaving with exertion. Sensing something had just happened, he looked inquiringly at Sura, who said irritably, ‘Well, what are you waiting for?’

Boerman petulantly flung a climbing harness at Nash’s feet.

‘Come on, hotshot, put it on!’

After fastening it to the nearest stout tree, the Afrikaner gave the rope a few tugs before launching outwards off the lip. In a hiss of hot nylon, he plummeted twenty-five metres in a single drop. Alighting smoothly on the topmost wedged log, he used it as a runway to pick up speed in one great bound, soaring across the chasm to land on another dead tree near the submarine’s bow. Here, he tested the integrity of the stack, jumping from log to log, with booming thuds that echoed around the sinkhole. Then he unhooked himself from the rope, barked a warning and, like a major league pitcher, flung the descender skywards to Nash, who snatched it painfully out of the air.

Sura watched on as he clipped himself to the rope.

‘Watch your step, Mr Nash, and remember your friends.’

It took him four attempts to land the gut-wrenching swing to the log jam. Nash had made the mistake of looking through the latticework of slippery tree trunks to the rocky floor of the sinkhole, a dizzying 100 metres below.

‘You’re afraid of heights, too?’ Boerman chortled delightedly. Standing unroped on a mossy log, he confidently thumped the hull of the submarine with a closed fist. ‘We need to climb around to the other side to access the deck. It will be easier to get down that way.’

Sura called down a warning to be careful.

‘Ja, ja!’ he yelled up. ‘I heard you the first time.’

The big man spotted a crack in the rusted steel plate. Wriggling his fingers inside, he used it to lunge up and grab hold of the bottommost torpedo door. Nash watched in ghoulish fascination as Boerman hauled himself bodily around the huge curvature of the hull. Without a safety rope, there was no room for error and, crazy as it was, there was something magnificent about it.

‘I’m on the deck!’ the Afrikaner eventually shouted down. ‘Get your bleddy ass up here!’