Closer inspection revealed it to be a battered aluminium cylinder, tapered at one end. A thick coating of slime and finger-like tendrils of weed growing on the bottom suggested it had been in the river for some time. A long-range fuel tank? Perhaps a parachute supply canister? A panel on the top was loose, hanging on by just one rivet.

‘Better look inside, Smithy,’ the skipper ordered. ‘You never know, it might be full of grog!’

‘Keep an eye on the bloody crocs then,’ the sailor muttered under his breath. While his mates held on to his legs, he leaned out over the murky water and swung the panel out of the way. With a gasp, he reeled back as a wave of hot, putrid air punched him in the face. ‘Stone me sideways, that bloody reeks!’

The cylinder had become a casket for a human body. Baked under the tropical sun, the skin of the corpse was a dark mummified parchment stretched tightly over protruding bones. Big white teeth grinned malevolently. Only the blond hair told them that he had been white.

‘Thinking of inviting him on board?’ some wag commented.

The crew laughed uneasily. A European corpse had rights, even in this godforsaken place. But they were a day from Wewak, and in this heat the boat would stink for a month.

‘Bring him around to the stern,’ said the skipper. ‘See if you can find some identification.’

He held the boat steady in the current, as the men manoeuvred the cylinder around to the transom step.

The luckless Smithy tried not to breathe, as he gingerly searched the tattered remains for dog tags.

‘Skip, you’d better take a look at this.’

The skipper stared in wonder at the silver objects. One was an Iron Cross with ‘M. H. 1941’ engraved on the back. The other was the unmistakable grinning death’s head badge of the Waffen SS. It didn’t make sense: German forces hadn’t been seen in Papua New Guinea since 1914, when Australian troops invaded the Kaiser’s colony at the outbreak of World War I.

The skipper sought the bosun’s advice. At thirty-one, he was the oldest man on board, and the only one who had encountered German troops while serving in the Mediterranean. The thickset man scrutinised the items intensely. Turning the medal over, he gave a low whistle.

‘It’s not an Iron Cross, Skip, it’s a silver Knight’s Cross with oak leaf cluster. They didn’t hand out too many of these.’

An extensive and unpleasant search revealed nothing else about M. H. There were no weapons, dog tags or a wallet, just a pair of huge size fifteen jackboots complete with femur and foot bones. Someone suggested the cylinder was a float from a seaplane. It seemed plausible; there were Japanese characters on one of the panels.

‘Skip,’ whined Smithy, ‘for the love of God, can we let him go now?’