'Yes, grandfather.' Susan took the piece of skull, and began sawing busily away.

The Doctor moved over to Barbara, who was staring blankly into the darkness, her face white and drawn. 'Don't think about failure,' said the Doctor gently. 'We shall get free, and we shall all escape from this terrible place.'

'What?'Barbara scarcely seemed to understand him.

'Try and remember how you and the others found your way here. Concentrate solely on that, retrace every step of the journey in your mind.'

'Yes, all right, if I can.' Barbara looked at him in surprise.

'You're trying to help me, aren't you?'

'Fear makes good companions of all of us, Miss Wright.'

'I didn't think you were ever afraid, Doctor.'

'Fear is with all of us, and always will be,' said the Doctor quietly. 'But so is the other sensation that always lives with it.'

'What sensation?'

'Your companion referred to it a little while ago. Hope, Miss Wright. Hope!'

Susan went on sawing at Ian's bonds until she too grew tired, then Barbara took over. All their work seemed to have made only the slightest impression on the thick leather thongs - it was obviously going to be a very long time before they were weakened enough to be broken.

Susan sat close to the Doctor, watching Barbara work. She was dozing a little when she heard a strange rustling sound behind her.

She turned around. In the far corner of the cave was a framework of branches, decorated with more of the ghastly, grinning skulls. The rustling was coming from that corner. To her horror, Susan saw that the skulls were moving. 'Look!' she screamed, and everyone turned round.

The pile of branches was pushed aside from behind, sending skulls bouncing and rolling across the floor. A ghastly figure appeared, a skinny old woman with straggling white hair. There was a long stone knife in her hand.

Brandishing it menacingly, she advanced upon the helpless prisoners. 'Fire is evil,' she chanted. 'You will not make fire!'

Hur nudged Za into wakefulness. He opened his eyes, reaching instinctively for his axe. Hur put her finger to her lips and led him between the piles of sleeping figures and outside the cave. They stood shivering in the night wind. Za blinked at her, rubbing the sleep from his eyes with his fists. 'What is it? Why do you wake me?

Tell me!'

'I saw the old woman take your knife.'

'If you saw - why did you let her? She is old. You could have held her.'

Hur answered his question with another. 'Why did she take it?'

'Who knows? Perhaps she has gone into the forest to hunt!'

'No,' said Hur. 'I have thought long on this. She has gone to kill the strangers.'

'Did she say this?'

'She took your knife. She is afraid of fire.'

'You should have stopped her.'

'Kal was in the cave. Leaders are awake when others sleep.

You must stop her.' Hur paused, looking hard at Za. 'The strange tribe will not be able to show you how to make fire if the old woman kills them.'

'But if I stop her from killing them they will give fire to me -

and not to Kal. Come!'

They hurried to the entrance to the cave of skulls - and saw the great stone still blocking the door.

'The old woman could not have gone into the cave,' said Za angrily. 'The stone is there. Why do you tell me this lie?'

Hur went to the cave mouth. She pressed her ear to the little gap between the stone and the edge of the cave entrance. She beckoned to Za. 'Listen!'

Za listened. 'I hear the old woman in the cave. She is talking to them.' Dropping his axe, Za began heaving the stone. At first it would not move, but gradually it started to rock, more and more. Hur ran to help...

It took the Doctor quite a while to realise what the old woman wanted. She was gabbling hysterically about fire, waving the knife threateningly at them. 'What does she want, Doctor?' sobbed Barbara.

'is she going to kill us?'

'No, I don't think so. As far as I can make out she's terrified of fire - she's offering to let us go if we promise not to make it.'

The old woman nodded eagerly. 'I will set you free, if you go away and do not make fire. Fire will bring trouble and death to the Tribe.'

'Let us go,' said the Doctor, instantly. 'Let us go and there will be no fire.'

They became aware of a grinding noise from the mouth of the cave. Someone was rocking the stone. There was a bellow of rage.

'Someone is coming,' said the Doctor. 'Quickly now!' He held out his wrists, and the old woman sawed at the bonds with the stone knife until they parted. 'Now my feet!' The old woman stooped and cut the bonds from the Doctor's feet. One by one she freed them.

All the time the great boulder blocking the entrance rocked more and more.

The old woman pointed to the way she had come in - there was a narrow opening concealed behind the bushes. 'You must hurry.

Follow the tunnel, and then take the path into the forest. You can hide there.'

'Hurry,' shouted Ian. 'They'll be here in a minute.' The Doctor went through the tunnel, then Barbara, then Susan and finally Ian himself.

Minutes after they had disappeared, the boulder shifted enough to leave a gap at the entrance. Za squeezed through, Hur close behind.

'Where are they?' roared Za.

Hur looked at the discarded lashings on the floor of the cave.

'She did not kill them. She has set them free.'

Za saw his knife in Old Mother's hand, and snatched it from her. 'Why, old woman? Why?'

'They would have made fire,' moaned Old Mother. 'They would have made fire.'

Hur's sharp eyes had spotted the opening at the back of the cave. 'They have gone this way. Here, Za!'

Za headed for the gap, and Old Mother wound her skinny arms around him, trying to hold him back. Angrily, Za threw her aside.

She stumbled to the floor, and lay there half-stunned.

Za peered into the tunnel and hesitated. 'They have gone into the night.'

Hur said, 'They have taken the secret of fire with them.'

'The beasts will kill them. They will kill us if we follow.'

Hur went back to the cave entrance, recovered Za's axe, and brought it back to him. She pressed it into his hand. 'You are the leader, Za,' said Hur softly. 'You are strong, as strong as the beasts.

You will be stronger still, once you know how fire is made. Stronger than Kal.'

Za looked at her for a moment, then slipped into the tunnel.

Hur followed him.

8

The Forest of Fear

It was dark in the forest.

The path was so narrow that lowlying branches whipped constantly across their faces, and they had to shield themselves with upheld arms as they ran.

The air was chill, though the forest protected them from the night winds. The path was so enclosed on each side and overhead that it was like running through a tunnel. Still, it was a thousand times better than the ghastly cave with its stench of death and shattered grinning skulls. Susan led the way, then Barbara, then Ian, with the Doctor in the rear. As they ran, Ian became aware that the Doctor was falling further and further behind.

He turned and saw that the old man had stopped running altogether. He was leaning panting against a tree. 'Stop! Just for a moment, please.'

'We must keep moving, Doctor.'

The Doctor nodded weakly. 'In a moment... in a moment.'

'We're not far enough away from the cave yet...'

'I know... I know. But I simply can't run any more!'

'Try!' urged Ian.

The Doctor nodded wearily, but he didn't move.

'All right,' said Ian. 'There's only one thing for it. I'll have to carry you.'

He advanced on the Doctor, who waved him indignantly away.