'There's Lucas in the chase car,' said Judy. He looked down and saw the Land-Rover bucketing along a track on the floor of the gorge and towing a trailer. 'That's one of the problems of ballooning; you have to have a way of getting back to where you started.'

Stafford looked up at the immensity of the envelope above, and then down again at the Land-Rover. It seemed strange that a structure the size of a six-storey office block could be folded up to fit in a small trailer. Ahead, rising from the floor of the gorge, was a big rock pillar, tapering to a needle point. 'Fischer's Column,' said Judy. She opened the lid of a box which was lashed to the side of the basket and took out a pair of binoculars. 'We should see rock hyrax. Believe it or not, they're the nearest relation to the elephant. Cuddly creatures.'

'Not too cuddly,' remarked Hunt. 'They carry rabies.'

They were now quite close to the ground, not more than fifty feet high, and Hunt was maintaining this height by short bursts of flame. For a moment Stafford thought they were going to crash into the rock column but they passed about twenty feet to one side. 'There,' said Judy. 'Those are hyrax.'

They were small animals which he would have taken to be rodents. A couple of dozen of them took fright and dashed for crevices in the rocks and disappeared. As they passed Hunt said, 'That's the closest I've been to Old Man Fischer. It's an old volcanic plug, you know.' He operated the burner control and the flame roared in a sustained burst. 'Up we go. There'll be bigger game ahead.'

The balloon rose and the strange landscape of Hell's Gate spread before them. The cliffs to the east were alive with birds which flew faster than any others Stafford had seen. Judy said they were Nyanza swifts. Ahead there was another, but smaller, rock column which he was told was called Embarta. As they rose above the cliffs the crater of the volcano Longonot came into view in the east and Hunt turned off the flame.

Stafford said, 'What kind of bigger game?'

'Oh, eland, zebra, impala – the usual inhabitants. Giraffe, perhaps.'

He saw them all. The zebra herds wheeled as the balloon shadow passed, and the giraffes galloped off in a rocking-horse canter. But none of the animals moved far away; as soon as the balloon drifted by they resumed their grazing and browsing placidly. Stafford said, 'Is this a game reserve?'

'Oh, no,' said Hunt. 'But there is plenty of game outside the reserves.' They were drifting lower and he had the binoculars to his eyes. 'Look there,' he said, handing them to Stafford. 'That tree by the big rock there. There's a leopard on the branch to the right. I wonder if he's the chap who's been visiting the College.' The leopard looked up incuriously, and yawned as the balloon went silently by.

'There's a lammergeier,' said Judy. There was an odd note of warning in her voice. Stafford looked to where she was pointing and saw a big bird circling.

Hunt said, 'That means our flight is nearly over. When the lammergeier goes up the balloon comes down.'

'Why?' asked Stafford. 'Is it likely to attack us?' He could imagine that a sharp beak and talons could make a few nasty rents in the thin fabric of the envelope.

Both Hunt and his sister went into fits of laughter. 'No,' Hunt said. 'A lammergeier wouldn't attack anything. He's a carrion eater. But when he's in the air it means that the ground has heated up enough to start thermals strong enough for him to soar. And balloons don't like thermals; the ride gets too bumpy and it can be positively dangerous. That's why we fly in the early morning.' He looked ahead. 'Still, we'll make it all the way through Hell's Gate.'

They all fell quiet and Stafford found himself in a dreamlike state, almost a trance. Ahead, on the crest of the pass, were puffs of white smoke drifting in the breeze and, from the ground, came the clear barking of baboons. They were nearly at the end of Hell's Gate and he saw, at last, why it was so named. What he had taken for smoke was steam escaping from a hundred fissures, and the violent hissing noise competed with the rumble of the balloon's flame.

'This is it,' said Hunt. 'Prepare for landing. Show Max how, Judy.'

She said, 'When Alan says "Now" crouch down in the basket and hang on to these rope handles – like this.' She demonstrated.

They passed over the steam jets and the balloon danced a little. There were flows of jagged lava which Stafford thought would do the balloon envelope a bit of no good should the balloon land among them. They went over those at a height of about fifty feet towards the open grassland beyond. Hunt said 'Now!' and Judy and Stafford crouched, but not before he had seen an eland looking at him with astonishment.

The basket made contact with the ground and he twisted his head to see Hunt yanking on a line. Above him the whole top of the envelope seemed to tear apart and he could see blue sky. Then the basket tipped on to its side and he was thrown on to his back alongside Judy. Everything was still and they had stopped moving.

'End of ride,' she said, and crawled out.

Stafford rolled out and stood up. Behind were the lava flows and steam clouds; ahead was the balloon envelope, looking very much as it had when he had first seen it, inert and dead upon the ground. In the distance the Land-Rover was driving towards them over the grass. Hunt was standing by the basket. He grinned and said, 'What does it feel like to be a hero of the sky?'

Stafford said slowly, 'I think that was the best damned experience I've had in my life.'

'You've not finished yet,' Hunt said. 'There's more to come. But first help me get the gas cylinders out."

They took out the cylinders and rolled them aside. The Land-Rover drove up and Lucas and the other Kenyans got out. Lucas came over carrying a hamper. 'Breakfast!' said Judy with satisfaction. She opened the hamper and took out plastic boxes. 'Cold chicken; boiled eggs, fruit. I hope I put the salt in – I can't remember.'

'You're forgetting the most important thing,' said Hunt, and stooped to pick up a large flask. 'It's an old ballooning tradition that anyone making a first flight ends up drinking champagne.' He opened the flask and took out a bottle. 'Nicely chilled,' he commented, and smiled. 'That's why we like to take up first-time passengers; that way we get to drink champagne, too.'

They sat on the empty cylinders eating breakfast and drinking champagne while Lucas and his friend packed up the balloon. It folded into a cube with dimensions of under four feet a side. After breakfast they climbed over the lava flows and had a look at the place where the steam was issuing. There was a strong smell of sulphur and the ground was hot underfoot.

Hunt pointed. 'Ol Karia is about two kilometres that way. They're drilling for steam there; gone down over five and a half thousand feet.'

Stafford looked at the steam issuing all around him. 'I don't see the point. Why drill that far down? There's plenty here.'

'Not this flabby stuff; you need high pressure steam to drive a turbine.'

Stafford shook his head. 'I don't think I'd like to live in a volcanic area. I prefer my terra to be firma.' 'Oh, it's fairly stable around here,' said Hunt. 'There was a quake in the Valley about four years ago but it didn't hurt much apart from taking out a piece of the road coming down the escarpment from Nairobi.'

Stafford turned and looked across at Longonot. The crater showed quite clearly. 'Is that an active volcano?'

'Not so as you'd notice. A few fumaroles, that's all. I'd call it quiescent. I've climbed into the crater. There are caves, some quite large, where gases have blown out. There are active volcanoes further south of here in Tanzania, notably Ol Doinyo Lengai.'

They turned to walk back to the Land-Rover and Stafford saw a taxi drawn up next to it and, much to his surprise, Hardin and Nair standing by. Hunt said in surprise, 'Now what are they doing here?'