The children heard a muffled growl. Jahna thought she saw a pale form, low-slung, stocky, move over the snow like a muscled ghost, trailing the deer. It might have been a cave lion. She shuddered.

“What now?” Millo whispered. “We can’t stay here.”

“No.” Jahna cast around. She saw that their ledge led down the cliff face to a hollow a few body’s lengths below. “That way,” she said. “I think it’s a cave.”

He nodded curtly. He led the way, edging his way down the narrow ledge, clinging to the chalk. But he was more frightened than he was prepared to admit, she realized.

At last, the perilous descent over, they threw themselves into the hollow and lay panting on the rough floor. The cave, worn in the chalk, reached back into dark recesses. The floor was littered with guano and bits of eggshell. It must be used as a nesting ground, by gulls, perhaps. There were blackened patches scattered over the floor — not hearths, but obviously the sites of fires.

“Look,” said Millo, his voice full of wonder. “Mussels.”

He was right. The little shellfish were piled up in a low heap, surrounded by a scattering of flint flakes. A flicker of curiosity made her wonder how they had got there. But hunger spoke louder, and the two of them fell on the mussels. Frantically they tried to prize open the shells with their fingers and stone blades, but the shells were stubborn and would not yield.

“Graah.”

They both whirled.

The gravely voice had come out of the darkness at the back of the cave. A figure came forward. It was a burly man, dressed in a wrap of what looked like deer hide — no, Jahna thought, not a man. He had a vast, prominent nose, and powerful stocky legs, and huge hands. This was a bonehead, a massive bull. He glared at them.

The children backed away, clutching at each other.

He had no name. His people did not give themselves names. He thought of himself as the Old Man. And he was old, old for his kind, nearly forty years old.

He had lived alone for thirty of those years.

He had been dozing at the back of this cave, in the smoky, comforting glow of the torches he kept burning there. He had spent the early morning combing the beaches below the cliffs at low tide, seeking shellfish. With the coming of evening he would soon have woken up anyway; evening was his favorite time of day.

But he had been disturbed early by the noise and commotion at the cave’s entrance. Thinking it might be gulls coming after his piles of shellfish — or something worse, an arctic fox maybe — he had come lumbering out into the light.

Not gulls, not a fox. Here were two children. Their bodies were tall and ludicrously spindly, their limbs shriveled and their shoulders narrow. Their faces were flat, as if squashed back by a mighty punch, their chins were pointed, and their heads bulged upward into comical swellings like huge fungi.

Skinny folk. Always skinny folk. He felt a vast weariness — and an echo of the loneliness that had once plagued his every waking moment and poisoned his dreams.

Almost without conscious thought he moved toward the children, his huge hands outstretched. He could crush their skulls with a single squeeze, or crack them together like two birds’ eggs, and that would be the end of it. The bones of more than one skinny robber littered the rocky beach below this cave; and more would join them before he grew too old to defend this, his last bastion.

The children squealed, grabbed each other, and scurried to the wall of the cave. But the taller one, a girl, pushed the other behind her. She was terrified, he could see that, but she was trying to defend her brother. And she was holding her nerve. Though panic piss trickled down the boy’s bare legs the girl kept herself under control. She dug into her jerkin and pulled out something that dangled on a string around her neck. “Bonehead! Bonehead man! Leave us alone and I’ll give you this! Pretty, pretty magic, bonehead man!”

The Old Man’s deep-set eyes glittered.

The pendant was a bit of quartz, a little obelisk, gleaming and transparent; its faces had been polished to shining smoothness, and one side had been painstakingly carved into a design that caught your eye and dazzled your mind. The girl swung the amulet back and forth, trying to draw his eyes, and she stepped forward from the wall. “Bonehead man, pretty, pretty…” The Old Man peered into blue eyes that stared straight back at him in that unsettling, direct way of the skinnies: a predator’s gaze.

He reached out and flicked at the amulet. It flew around the girl’s neck and smashed against the wall behind her. She yelped, for its leather string had burned her neck. The Old Man reached out again. It could be over in a heartbeat.

But the children were jabbering again, in their fast, complicated language. “Make him go away! Oh, make him go away!” “It’s all right, Millo. Don’t be afraid. Your great-grandfather is inside you. He will help you.”

The Old Man let his huge hands drop to his sides.

He looked back at the mussels they had tried to take. The shells were scraped and chipped — one showed teeth marks — but not one was broken open. These children were helpless, even more so than most of their kind. They couldn’t even steal his mussels.

It had been a long time since voices of any kind had been heard in this cave — any save his own, and the ugly cawing of gulls or the barking of foxes.

Not quite understanding why, he stalked off to the back of his cave. Here he stored his meat, his tools, and a stock of wood. He brought back an armful of pine logs, brought down from the forested area at the top of the cliff, and dumped them close to the entrance of the cave. Now he fetched one of his torches, a pine branch thick with resin and bound up with fat-laden sealskin. The torch burned steadily but smokily, and would stay alight all day. He set the torch on the ground and began to heap wood over it.

The children still cowered against the wall, eyes wide, staring at him. The boy pointed at the ground. “Look. Where’s his hearth? He’s making a mess…” The girl clamped her hand over his mouth.

When the fire was burning brightly, he kicked it open to expose red-hot burning logs within. Then he picked up a handful of mussels and threw them into the fire. The mussels’ shells quickly popped open. He fished them out with a stick and scooped out their delicious, salty contents with a blunt finger, one after another.

The boy squirmed and got his mouth free. “I can smell them. I’m hungry.”

“Hold still; just hold still.”

When the Old Man had had his fill of the mussels he lifted his leg, let out a luxurious fart, and clambered painfully to his feet. He lumbered to the entrance to his cave. There he sat down with one leg folded under him, the other straight out, with his skin wrap over his legs and crotch. He picked up a flint cobble he had left there days before. Using a granite pebble as a hammer-stone he quickly began to shape a core from the flint. Soon waste flakes began to accumulate around his legs. He had seen dolphins today. There was a good chance one of those fat, lithe creatures might be washed up on the shore in the next day or two, and he needed to be prepared, to have the right tools ready. He wasn’t planning, exactly — he wasn’t thinking as a skinny might have thought — but a deep intuition of his environment shaped his actions and choices.

As he let his hands work — shaping this lump of compressed Cretaceous fossils, as the hands of his ancestors had worked for two hundred and fifty millennia — he gazed out to the west, where the sun was starting to set over the Atlantic, turning the water to a sheet of fire.

Behind him, unnoticed, Jahna and Millo crept to the fire, threw on more mussels, and gulped down their salty flesh.