From her bag she placed a dossier on the desk and extracted a grainy photo.

‘This is the I-403, a 120-metre-long Japanese Sentoku submarine, which left Kure Naval Base more than seventy years ago for the Nazi port of Lorient. It was carrying a large consignment of gold and raw opium, payment for German uranium oxide which was to be its return cargo. With it the Japanese planned to construct a so-called dirty bomb.’

Her father studied the picture. ‘I recall they found the wreck in the Atlantic some years ago, but at two miles down were unable to salvage her.’

‘That was actually the I-52, a cargo submarine.’ Sura said this delicately, as her father hated being contradicted. ‘As defeat loomed, the desperate Japanese launched several of these Yanagi, or trade missions, using every submarine type capable of the range. Only one ever made it. The rest were presumed sunk.’

‘But what’s this got to do with M. H?’

She pressed on quickly. ‘The I-403 sailed on the twentieth of April 1945. Two weeks later, her mission ended because Hitler killed himself. But she never returned to port, nor was she reported sunk.’ Spreading out a map of the South China Sea, Sura pointed to an island on the southern tip of the Philippines. ‘A US coast watcher on Jolo Island spotted her on the surface, early morning on the fifth of May, bearing south-east.’

‘Away from Japan?’

‘It’s the last confirmed sighting.’

Her father raised his eyebrows. ‘Doesn’t sound very Japanese. They would have fought to the last man, woman and child, had Hirohito not conceded after Nagasaki.’

‘You are right, Father. But it wasn’t only Japanese personnel on board. The gold was escorted by a detachment of elite Nazi troops, none other than the Leibstandarte SS Adolf Hitler, stationed at the German Embassy in Tokyo.’ She placed a black and white photograph on the desk. ‘And this was their commander, SS Standartenführer Martin Heider.’

Her father hissed between his teeth. ‘M. H.’

Heider was classically handsome, his face dominated by a straight blade of a nose, a powerful square jaw, and well-defined lips. He might have been attractive, but for his eyes, which were frighteningly devoid of emotion.

‘You’ve found him, Sura!’ The general’s quick eyes latched on to hers, then widened. ‘You think he stole the gold?’

She nodded eagerly. ‘With a king’s ransom there for the taking, why would Heider and his men willingly surrender, only to be executed for war crimes?’ She placed her finger on the map and began tracing a line. ‘Assuming they commandeered the submarine, they would have headed east to dodge the US invasion fleet. Across the Celebes Sea, past Halmahera Island, along the northern coastline of New Guinea . . . looking for somewhere to hide.’ She tapped her finger on the mouth of the Sepik River. ‘Somewhere no one would ever think of looking for them.’