'This first,' said Tiger Dan, in a brutal voice, and he picked up an enormous stone. He threw it with all his force at poor Pongo, who tried to leap out of the way. But the rope prevented him, and the stone hit him full on the head.

He gave a loud scream and fell down at once, lying quite still.

'You've gone and killed him,' said Lou.

'So much the better!' said Tiger Dan. 'Now let's go and see if the entrance-hole is open. Those kids want their necks wringing!'

They went to the hollow and saw at once that the hole had been discovered, opened, and that the children must have gone down it.

'They're down there now,' said Tiger Dan, almost choking with rage. 'Shall we go down and deal with them - and get our stuff and clear off? We meant to clear off tomorrow, anyway. We might as well get the stuff out now.'

'What - in the daylight - with any of the farm men about to see us!' said Lou with a sneer. 'Clever, aren't you?'

'Well, have you got a better idea?' asked Tiger Dan.

'Why not follow our plan?' said Lou. 'Go down when it's dark and collect the stuff. We can bring our wagon up as we planned to do tonight. We don't need to bother about forcing the children to go now - they're underground - and we can make them prisoners till we're ready to clear off!'

'I see,' said Dan, and he grinned suddenly, showing his ugly teeth. 'Yes - we'll close up the hole and run the caravan back over it - and come up tonight in the dark with the wagon - go down - collect everything - and shut up the hole again with the children in it. We'll send a card to Gorgio when we're safe and tell him to go up and set the kids free.'

'Why bother to do that?' said Lou, in a cruel voice. 'Let 'em starve underground, the interfering little beasts. Serve 'em right.'

'Can't do that,' said Dan. 'Have the police after us worse than ever. We'll have to chuck some food down the hole, to keep them going till they're set free. No good starving them, Lou. There'd be an awful outcry if we do anything like that.'

The two men carefully put back the boards over the top of the hole and replaced the heather tufts. Then they ran the caravan back over the place. They looked at Pongo. The chimpanzee was still lying on his side, and the men could see what a nasty wound he had on his head.

'He ain't dead,' said Lou, and gave him a kick. 'He'll come round all right. Better leave him here. He might come to himself if we carried him back to camp, and fight us. He can't do us any harm tonight, tied up like that.'

They went away down the track. Not ten minutes afterwards the children came to the hole and found it blocked up! If only they hadn't stopped to explore that tunnel a bit further, they would have been able to get out and set Timmy on the two men.

But it was too late now. The hole was well and truly closed. No one could get out. No one could find poor Pongo and bathe his head. They were real prisoners.

They didn't like it at all. Anne began to cry, though she tried not to let the others see her. n.o.bby saw that she was upset, and put his arm round her.

'Don't cry, little Anne,' he said. 'We'll be all right.'

'It's no good staying here,' said Julian, at last. 'We might as well go somewhere more comfortable, and sit down and talk and eat. I'm hungry.'

They all went back down the pa.s.sage, up through the hole in the roof, and into the enormous cavern. They found a sandy corner and sat down. Julian handed Anne the kitbag and she undid it to get the food inside.

'Better only have one torch going,' said Julian. 'We don't know how long we'll be here. We don't want to be left in the dark!'

Everybody immediately switched off their torches. The idea of being lost in the dark inside the hill wasn't at all nice! Anne handed out slices of bread and b.u.t.ter, and the children put thin slices of Mrs Mackie's delicious ham on them.

They felt distinctly better when they had all eaten a good meal. That was jolly good,' said d.i.c.k. 'No, we won't eat that chocolate, Anne. We may want it later on. Golly, I'm thirsty!'

'So am I,' said n.o.bby. 'My tongue's hanging out like old Timmy's. Let's go and get a drink.'

'Well, there was a stream in that other cave beyond the tunnel, wasn't there?' said d.i.c.k. 'We can drink from that. It'll be all right.'

'Well, I hope it will,' said Julian. 'We were told not to drink water that wasn't boiled while we were caravanning - but we didn't know this sort of thing was going to happen! We'll go through the tunnel and get some water to drink from the stream.'

They made their way through the long, winding tunnel, and pa.s.sed the shelf of stolen goods. Then on they went and came out into the cave through which the stream rushed so quickly. They dipped in their hands and drank thirstily. The water tasted lovely - so clear and cold.

Timmy drank too. He was puzzled at this adventure, but so long as he was with George he was happy. If his mistress suddenly took it into her head to live underground like a worm, that was all right - so long as Timmy was with her!

'I wonder if this stream does go to that hole in the hillside, and pours out there,' said Julian, suddenly. 'If it does, and we could follow it, we might be able to squeeze out.'

'We'd get terribly wet,' said George, 'but that wouldn't matter. Let's see if we can follow the water.'

They went to where the stream disappeared into a tunnel rather like the dry one they had come along. Julian shone his torch into it.

'We could wade along, I think,' he said. 'It is very fast but not very deep. I know - I'll go along it myself and see where it goes, and come back and tell you.'

'No,' said George, at once. 'If you go, we all go. You might get separated from us. That would be awful.'

'All right,' said Julian. 'I thought there was no sense in us all getting wet, that's all. Come on, we'll try now.'

One by one they waded into the stream. The current tugged at their legs, for the water ran very fast. But it was only just above their knees there. They waded along by the light of their torches, wondering where the tunnel would lead to.

Timmy half-waded, half-swam. He didn't like this water-business very much. It seemed silly to him. He pushed ahead of Julian and then a little further down, jumped up to a ledge that ran beside the water.

'Good idea, Tim,' said Julian, and he got up on to it too. He had to crouch down rather as he walked because his head touched the roof of the tunnel if he didn't - but at least his legs were out of the icy-cold water! Ail the others did the same, and as long as the ledge ran along beside the stream they all walked along it.

But at times it disappeared and then they had to wade in the water again, which now suddenly got deeper. 'Gracious! It's almost to my waist,' said Anne. 'I hope it doesn't get any deeper. I'm holding my clothes up as high as I can, but they'll get soaked soon.'

Fortunately the water got no deeper, but it seemed to go faster. 'We're going down hill a bit,' said Julian at last. 'Perhaps we are getting near to where it pours out of the hill.'

They were! Some distance ahead of him Julian suddenly saw a dim light, and wondered whatever it could be. He soon knew! It was daylight creeping in through the water that poured out of the hole in the hillside - poured out in a torrent into the sunshine.

'We're almost there!' cried Julian. 'Come on.'

With light hearts the children waded along in the water. Now they would soon be out in the warm sunshine. They would find Pongo, and race down the hill in the warmth, catch the first bus, and go to the police station.

But nothing like that happened at all. To their enormous disappointment the water got far too deep to wade through, and n.o.bby stopped in fright. 'I dursent go no further,' he said. 'I'm almost off my feet now with the water rushing by.'

'I am, too,' said Anne, frightened.

'Perhaps I can swim out,' said Julian, and he struck out. But he gave it up in dismay, for the torrent of water was too much for him, and he was afraid of being hurled against the rocky sides and having his head cracked.

It's no good,' he said, gloomily. 'No good at all. All that wading for nothing. It's far too dangerous to go any further - and yet daylight is only a few yards ahead. It's too sickening for words.'

'We must go back,' said George. 'I'm afraid Timmy will be drowned if we don't. Oh, dear - we must go all that way back!'

CHAPTER TWENTY