'You'll do no such thing, young man. I don't need your help. I may be old, but I'm not senile. I just want to get my breath back, that's all.'

Ian looked despairingly at Susan. She came forward and said,

' Please, grandfather.'

The Doctor sighed and hoisted himself wearily from the trunk.

They moved on, though this time at a slower pace. There were mysterious rustlings in the forest around them, and the cries of wild beasts.

Barbara moved up close to Ian. 'Are you sure this is the right way?'

'I think so. We want to cut off the corner of the forest and get back to the ship. We came in to the forest at a different place - it's hard to be sure. What do you think?'

'I can't remember, Ian. I simply can't remember!'

There was hysteria in her voice.

Ian put a consoling hand on her shoulder. 'Never mind, we're free, aren't we? That's the main thing.'

They moved on their way.

Ian heard a noise in the darkness behind him and whirled round. The bushes seemed to be moving slightly, and he thought he heard a low throaty sound, like the purring of a giant cat...

'What is it?'

Ian shrugged. 'Just some wild animal or other. Probably more scared of us than we are of it.'

But in his heart Ian wasn't too sure. He racked his brains to remember what animals had been about in the days of the cavemen.

Not dinosaurs, at least, though that was a common mistake.

Luckily for man, these great monsters had been long extinct. But mammoths certainly. And what about the sabre-toothed tiger? Surely that had been around?

Cautiously they moved on through the dark forest. They came to a fallen tree, and paused to take their bearings.

'I remember this place,' said Susan excitedly. 'But we didn't go right by it, we went around.'

'That's right,' agreed Barbara. 'The trail passed it on one side.'

'I hope you're both right,' said Ian. 'Because if you are, the ship can't be very far away.' He turned to the Doctor, who was leaning on Susan's shoulder. 'How are you feeling?'

'I'm quite all right, thank you, young man! Don't keep regarding me as the weak link in this party.'

Suddenly, Barbara gave a little scream, and moved closer to Ian.

'What is it?'

'I don't know. I thought I saw something move - over there in the bushes.'

'Nonsense,' said the Doctor airily.

'I tell you the bushes moved, I saw them. We're never going to get out of this terrible place. Never!'

'What could it have been, grandfather?' whispered Susan.

'Imagination, my dear child. Pure imagination,' said the Doctor, but he looked round rather uneasily.

Ian put a consoling arm around Barbara's shoulders. 'Look, I know this seems like a nightmare, but we'll get out of it.'

'We'll all die in this terrible forest, I know we will!'

'No we won't,' said Ian gently. 'Not if we don't give up.'

'Ian, what's happening to us?'

'Look, we can't be far from the ship now. We'll be safe there.

We got out of the caves, didn't we?'

Susan moved closer to the Doctor and shivered. 'It's so cold!'

The Doctor slipped off his jacket and put it round her shoulders. 'You're welcome to this, my child.'

'What about you, grandfather?'

The Doctor managed a smile.

'Don't worry about me. All this exertion has made me quite hot!'

Ian came over to them. 'Barbara's feeling the strain a bit. We seem to have stopped anyway, so we'll rest here for a little while.'

Susan nodded gratefully. 'Is there any chance of their following us?'

'I'm afraid there is!'

'That's why I don't want to stay here too long.'

'You don't think I want to linger, do you?' said the Doctor peevishly.

Ian gave him a long-suffering look. 'No, of course, I don't. I think we'll change the order when we set off again. You lead, with Susan and Barbara, and I'll bring up the rear.'

The Doctor bristled. 'You seem to have elected yourself leader of this little expedition.'

'There isn't time to take a vote on it, is there?'

'Just so long as you understand that I won't follow your orders blindly, young man.'

Ian leaned forward. 'Believe me, Doctor, if there were just the two of us, as far as I'm concerned you could find your own way back to the ship!'

'You're a very tiresome young man, aren't you?'

'And you're a very stubborn old one,' said Ian, through gritted teeth. 'But when we set off, you'll lead, the girls will come in between, and I'll go last - that's the safest way!'

'Safest? Why safest?'

'I think Barbara is right. I heard something in the bushes behind us when we stopped before, and it's still with us now.

Something's stalking us.'

'Sheer imagination!'

'What makes you so confident, Doctor?'

'I refuse to be frightened out of my wits by mere shadows!'

Ian gave up. 'Very well, suit yourself. We'll rest here for a little while longer, and then move on.'

In another part of the forest, Za and Hur too had paused, though not to rest. They knelt, examining the traces left by the strangers on their passage through the jungle - markings as clear to them as road signs to a modern motorist.

'Here is a broken twig,' said Hur. 'They rested here.'

Za examined a footprint. 'They have strange feet.'

'They wore skins on them,' said Hur. 'There are more marks here, and here. They went this way.'

There was a distant rustle ahead of them, and a low growling.

Za looked fearfully at Hur. 'It was wrong to follow them. We should not have done this.'

'We cannot go back now. Would you have Kal mock you as you mocked him?'

Za took a firmer grip on his axe and they went on their way.

The little party moved on through the jungle, inevitably slowed down by the fact that the Doctor was now in the lead. Barbara caught her foot in a trailing vine and fell, crashing into the bushes to one side of the path. Her outstretched hand touched something warm and wet. Stumbling to her feet she looked at her hand. It was covered with blood. She screamed.

On the trail behind them, Za cocked his head alertly. 'They are very near now. That was one of the women. Come!' They hurried on.

The Doctor was examining the huddled shape just beside the path. 'What is it, grandfather?' asked Susan fearfully.

'Only a dead animal. Some kind of deer, I think. It's been killed very recently, the body is still warm.'

'What killed it?'

'Judging by these claw marks, some very large and very savage member of the cat family - possibly a sabre-toothed tiger.'

Suddenly, they heard a crashing in the jungle behind them.

'It is the tiger?' whispered Barbara.

'Too noisy. It must be the cave people, coming after us. We'll have to hide, and hope they pass by. Quick, over there in the bushes.'

Ian thrust them into the bushes, and they crouched down, waiting.

Seconds later, two skin-clad figures ran into the clearing, and paused, looking around them.

One was a massive figure carrying a stone-headed axe - one of the men they had seen at the cave.

The figure beside him was both smaller and slighter. To his astonishment, Ian saw that it was a girl.

The two savage figures stood poised, peering around them suspiciously.

Close by in the bushes, the great cat was also poised. It had followed this strange prey through the forest for quite some way.

Several times it had crouched to spring and bring one of them down, but each time something had held it back. There was something very wrong about these creatures. Their appearance, the way they crashed boldly through the jungle, and above all the alien smell of the strange skins they wore, all this was new, unknown - and possibly dangerous.