Only two birds, Leon thought. They might be strays. There would have been more of them if . . . From directly ahead he heard the loud flapping of heavy wings and another vulture rose from beyond the screen of banana plants. Leon felt the chill of dread. If the brutes are settling that means there’s meat lying out there, dead meat.

Again he signalled the halt. He stabbed a finger at Manyoro, then went forward alone, Manyoro backing him. Even though his approach was stealthy and silent he alarmed more of the huge carrion-eaters. Singly and in groups they rose on flogging wings into the blue sky to join the spiralling cloud of their fellows.

Leon stepped past the last banana plant and stopped again at the edge of the open parade-ground. Ahead, the mud-brick walls of the boma glared, with their coating of limewash. The front door of the main building stood wide open. The veranda and the baked-clay surface of the parade-ground were littered with broken furniture and official government documents. The boma had been ransacked.

Hugh Turvey and his wife, Helen, lay spreadeagled in the open. They were naked and the corpse of their five-year-old daughter lay just beyond them. She had been stabbed once through her chest with a broad-bladed Nandi assegai. Her tiny body had drained of blood through the massive wound, so her skin shone white as salt in the bright sunlight. Both her parents had been crucified. Sharpened wooden stakes had been driven through their feet and hands into the clay surface.

So the Nandi have learned something at last from the missionaries, Leon thought bitterly. He took a long, steady look around the border of the parade-ground, searching for any sign that the attackers might still be near by. When he was satisfied that they had gone, he went forward again, stepping carefully through the litter. As he drew closer to the bodies he saw that Hugh had been crudely emasculated and that Helen’s breasts had been cut off. The vultures had enlarged the wounds. The jaws of both corpses had been wedged wide apart with wooden pegs. Leon stopped when he reached them and stared down at them. ‘Why are their mouths prised open?’ he asked, in Kiswahili, as his sergeant came up beside him.

‘They drowned them,’ Manyoro answered quietly, in the same language. Leon saw then that the clay beneath their heads was stained where some spilled liquid had dried. Then he noticed that their nostrils had been plugged with balls of clay – they must have been forced to draw their last breaths through their mouths.

‘Drowned?’ Leon shook his head in incomprehension. Then, suddenly, he became aware of the sharp ammonia stink of urine. ‘No!’

‘Yes,’ said Manyoro. ‘It is one of the things the Nandi do to their enemies. They piss in their open mouths until they drown. The Nandi are not men, they are baboons.’ His contempt and tribal enmity were undisguised.

‘I would like to find those who did this,’ Leon muttered, disgust giving way to anger.

‘I will find them. They have not gone far.’

Leon looked away from the sickening butchery to the heights of the escarpment that stood a thousand feet above them. He lifted his slouch hat and wiped the sweat from his brow with the back of the hand that held the Webley service revolver. With a visible effort he brought his emotions under control, then looked down again.

‘First we must bury these people,’ he told Manyoro. ‘We cannot leave them for the birds.’

Cautiously they searched the buildings and found them deserted, with signs that the government staff had fled at the first hint of trouble. Then Leon sent Manyoro and three askari to search the banana plantation thoroughly and to secure the outside perimeter of the boma.

While they were busy, he went back to the Turveys’ living quarters, a small cottage behind the office block. It had also been ransacked but he found a pile of sheets in a cupboard that had been overlooked by the looters. He gathered up an armful and took them outside. He pulled out the stakes with which the Turveys had been pegged to the ground, then removed the wedges from their mouths. Some of their teeth were broken and their lips had been crushed. Leon wetted his neckerchief with water from his canteen and wiped their faces clean of dried blood and urine. He tried to move their arms to their sides but rigor mortis had stiffened them. He wrapped their bodies in the sheets.

The earth in the banana plantation was soft and damp from recent rain. While he and some of the askari stood guard against another attack, four others went to work with their trenching tools to dig a single grave for the family.

On the heights of the escarpment, just below the skyline and screened by a small patch of scrub from any watcher below, three men leaned on their war spears, balancing easily on one leg in the stork-like attitude of rest. Before them, the floor of the Rift Valley was a vast plain, brown grassland interspersed with stands of thorn, scrub and acacia trees. Despite its desiccated appearance the grasses made sweet grazing and were highly prized by the Masai, who ran their long-horned, hump-backed cattle on them. Since the most recent Nandi rebellion, though, they had driven their herds to a safer area much further to the south. The Nandi were famous cattle thieves.

This part of the valley had been left to the wild game, whose multitudes swarmed across the plain as far as the eye could see. At a distance the zebra were as grey as the dustclouds they raised when they galloped skittishly from any perceived danger, the kongoni, the gnu and the buffalo darker stains on the golden landscape. The long necks of the giraffe stood tall as telegraph poles above the flat tops of the acacia trees, while the antelope were insubstantial creamy specks that danced and shimmered in the heat. Here and there masses of what looked like black volcanic rock moved ponderously through the lesser animals, like ocean-going ships through shoals of sardines. These were the mighty pachyderms: rhinoceros and elephant.

It was a scene both primeval and awe-inspiring in its extent and abundance, but to the three watchers on the heights it was commonplace. Their interest was focused on the tiny cluster of buildings directly below them. A spring, which oozed from the foot of the escarpment wall, sustained the patch of greenery that surrounded the buildings of the government boma.

The oldest of the three men wore a kilt of leopard tails and a cap of the same black and gold speckled fur. This was the regalia of the paramount witch doctor of the Nandi tribe. His name was Arap Samoei and for ten years he had led the rebellion against the white invaders and their infernal machines, which threatened to desecrate the sacred tribal lands of his people. The faces and bodies of the men with him were painted for war: their eyes were circled with red ochre, a stripe was painted down their noses and their cheeks were slashed with the same colour. Their bare chests were dotted with burned lime in a pattern that simulated the plumage of the vulturine guinea fowl. Their kilts were made of gazelle skins and their headdresses of genet and monkey fur.

‘The mzungu and his bastard Masai dogs are well into the trap,’ said Arap Samoei. ‘I had hoped for more, but seven Masai and one mzungu will make a good killing.’

‘What are they doing?’ asked the Nandi captain at his side, shading his eyes from the glare as he peered down the precipitous slope.

‘They are digging a hole to bury the white filth we left for them,’ said Samoei.

‘Is it time to carry the spears down to them?’ asked the third warrior.

‘It is time,’ answered the paramount witch doctor. ‘But keep the mzungu for me. I want to cut off his balls with my own blade. From them I will make a powerful medicine.’ He touched the hilt of the panga on his leopardskin belt. It was a knife with a short, heavy blade, the favoured close-quarters weapon of the Nandi. ‘I want to hear him squeal, squeal like a warthog in the jaws of a leopard as I cut away his manhood. The louder he screams the more powerful will be the medicine.’ He turned and strode back to the crest of the rugged rock wall, and looked down into the fold of dead ground behind it. His warriors squatted patiently in the short grass, rank upon rank of them. Samoei raised his clenched fist and the waiting impi sprang to its feet, making no sound that might carry to their quarry.