'And so we wait,' grumbled Horg. 'Za talks - and we have no meat, no fruits from the trees, no roots. Za is no leader.'

'If Za could hear you speak, he would kill you,' said Hur angrily.' You would lie on the old stone till your blood runs out.'

'Perhaps Za is letting the strangers go,' said Horg suspiciously.

'Perhaps he is setting them free, as Old Mother did.'

'It is a lie,' shouted Hur. 'Za sent a warrior to watch over the cave. He told him to kill the strangers if they came out.'

But the muttering went on. Hur, listened, worried. Unless Za acted soon, the Tribe would turn on him and destroy him.

The sentry outside the cave was not a very alert guard. Like all Za's people, he lacked the discipline for any prolonged task. Besides, what was the point of guarding the strangers when Za was with them?

Kal dropped from the rock above, soft-footed like a great cat, and took the guard around the throat from behind.

For a moment they stood locked in silent struggle, Kal's muscles swelling with the effort. Then the guard fell dead to the ground.

Kal drew his knife, and slipped into the tunnel that led to the cave of skulls.

The little blaze had been built up into a proper fire, blazing merrily in the centre of the cave. His brow furrowed, Za listened as Ian explained the working of the fire-bow.

The leaping flames cast giant shadows on the wall - and suddenly Susan realised that one of the shadows was not their own.

A sixth shadow, huge and menacing, loomed high on the cave wall.

'Look!' screamed Susan.

They turned and saw Kal, knife in hand, advancing from the back of the cave.

Za snatched up his axe, and went to meet him.

For a moment they circled around the fire, eyeing each other, and then simultaneously, both sprang to the attack. It was a savage, brutal fight - all the more savage because soon both men lost their weapons. A lucky blow from Za's axe shattered Kal's knife to fragments. As Za raised the axe to strike, Kal sprang in beneath it, grappling with him. For a moment they struggled for possession of the axe. Suddenly Kal twisted it from Za's grasp, losing hold of it himself in the process. The axe clattered to the floor, and from then on the two men fought like wild animals with teeth and claws.

Susan buried her head on Barbara's shoulder and both looked away. Ian watched the fight with horrified fascination. The Doctor looked on dispassionately, following the progress of the battle like some Roman emperor watching two gladiators in the arena.

For some time it was hard to tell who was gaining the upper hand. Za was bulkier and stronger, but Kal was quicker and lithe as a cat. Time and time again, he twisted free from Za's hold. But Za's greater strength gave him victory in the end. Catching Kal in a terrible grip, he hurled him bodily to the ground. As Kal lay there half-stunned, Za snatched up a great rock and brought it smashing down...

Now there was one more shattered skull in the cave of skulls.

Outside the cave, the Tribe was growing impatient. As the first rays of the sun struck the stone of sacrifice, Horg gave an angry roar.

'Orb is above us, and still there is no fire. Orb waits for his sacrifice!

Call Za! Tell him to bring the strangers from out of the cave of skulls! If he does not we will sacrifice him with them!'

Za dragged Kal's body to the back of the cave, picked up his axe, and came slowly back to the fire. There was blood on his hands.

'Kal is dead now. I am leader - and we have fire!'

Suddenly there came the sound of angry shouts from outside the cave.

'Za! Za! Bring out the strangers! The strangers must be sacrificed to Orb!'

'Za! Za! Za!'

The chanting grew louder, angrier.

Ian took a long stick and lit the end in the fire. He handed it to Za. 'Here! Show this to your tribe!'

Za took the blazing branch. 'You will wait here.'

'We'll come out with you.'

'No. You will wait here!'

Holding the blazing branch high above him, Za went through the tunnel.

Angrily Ian watched him go. 'Why can't we go with him?'

'It might be safer in here,' said the Doctor. 'Let him go, Chesterton, let him go. Let him show the Tribe fire, establish his leadership. Then he'll set us free.'

The chanting came to an instant halt when Za marched out of the cave bearing his blazing torch.

He advanced on the circle of warriors, and they shrank fearfully back. Za held out the torch. 'Fire!'

Horg stretched out his hand to the flames, and nodded reverently.

Za looked challengingly around the circle. 'Kal is dead. I give you fire. I am the leader.'

Horg bowed his head. 'Yes. You are the leader.'

'We shall give food and water to the new tribe in the cave of skulls,' ordered Za.

'There is no meat.'

Za looked at the rising sun. 'I shall go into the forest and bring back meat.'

Horg licked his lips hungrily. 'Yes. I remember how well the meat and the fire join together.'

'We shall join them again. Guard the new tribe well. They must be here when I get back. The rest of you gather wood. We shall keep the fire alive in the great cave.'

Za handed the blazing branch to Horg, and headed for the forest.

Hur watched him go, her eyes shining with pride. 'Bring fruit and water,' she ordered. 'I must feed the new tribe - as Za, the leader, commands.'

Inside the cave of skulls, the wait seemed endless. 'It didn't work,' said Ian. 'He's going to keep us here.'

'Someone's coming,' called Susan.

Hur came into the cave carrying fruit wrapped in a piece of skin.

'Look, what's going on?' demanded Ian. 'Why are we being kept here?'

Hur put the fruit down by the fire. 'Za has gone into the forest to hunt. Later there will be meat for you.'

'Why can't we go outside?' asked Barbara. 'Please let us go out,' pleaded Susan. 'It's terrible in here.'

'Za has ordered that you stay. Za is the leader.'

'But we helped you! We even gave you fire.'

'Yes, we have fire now,' said Hur flatly.

Hur started to move away, but Barbara caught her by the arm.

'How long have we got to stay in here? How long must we stay with you?'

'Forever,' said Hur simply. Pulling herself free, she turned and left the cave.

'We have fire now,' mimicked Ian bitterly. 'Yes, and I was the one who gave it to them - like a fool. I should have waited, bargained with them...'

'Don't worry, my boy, you did the right thing,' said the Doctor.

'The only possible thing.'

Barbara nodded. 'At least we're still alive. We'd have been sacrificed by now if we hadn't given them fire.'

Susan looked round the gloomy cave. The light from the little fire played eerily on the shattered skulls.

'Forever,' she whispered. 'You heard what she said. They're going to keep us here forever...'

12

Escape into Danger

Ian Chesterton woke out of a nightmare-haunted sleep, to find that the nightmare was real. He was still in the cave of skulls.

Barbara was shaking him gently by the shoulder. 'Ian, wake up.

You've slept most of the day. The Doctor says it'll be dark again soon.'

Ian sat up and looked around. Susan and Barbara were sitting beside him, and the Doctor was adding branches to the fire.

'They've brought us some meat,' said Susan. 'I think it's supposed to be cooked.' She pointed to a leaf on which were a few chunks of charred and bloody meat.

'There's some water too,' said Barbara, 'in a kind of hollow stone. We saved you some.'