The politics of the thing had proved tedious and it would be tedious to recount them. It is enough to say that a year later Mendoza got a UN grant to test his theory – which was that in the Mendoza Effect lay the possibility of a major alleviation of the world's power crisis.

His claim was simple, staggering, and well-documented, though the theory was a long way ahead of the Saharan evidence and only comprehensible to a few experts. With his two Saharan electrodes he had achieved a maximum output of 3.2 kilowatts. But (his theory said) given two pairs of Moho electrodes, each electrode being 117.3 kilometres from its partner, and the two pairs being separated by the diameter of the globe – and given a phased stimulus of a few kilowatts, synchronized by orbiting satellite, being fed to those four electrodes – the output from each pair would be of the order of several thousand megawatts.

The UN Secretary-General didn't understand it either and the experts he consulted contradicted each other. But he had a feeling about this serious young Spaniard; and anyway laser drilling was getting cheaper by the month. So he took a chance and pushed Project Mohowatt through the appropriate Committee.

On 15 March 1997 Dr Juan Jesus Mendoza ran his first test on the completed Mohowatt prototype, which had one station near Obidos in Brazil and the other near Manado in the Celebes. His input at each station was 150 kilowatts and his output at each was 4015 megawatts. Once the process was started, controlled feedback from the output supplied the necessary input.

The UN Secretary-General in person made a splendid speech at the inaugural demonstration to diplomats and the media. But Mendoza remembered better his chief engineer's comment afterwards: 'He doesn't understand it? Hell, Juan, I don't understand it, and I built the thing for you! But this gizmo hauls itself up by its own bootstraps and if we don't watch that feedback like bloody hawks, it could blow the roof.'

Enlightened world opinion congratulated itself that the Mohowatt principle was UN-sponsored and so freely available to any nation wishing to exploit it. Practically all of them did, though some were at a disadvantage if thousands of fathoms of sea covered their globally opposite areas; but even they could console themselves with the knowledge that much cheaper power would soon be purchasable from not-too-distant neighbours, who would be undercutting each other to sell it to them. By the turn of the century, over a hundred Mohowatt couples were in operation round the globe, with as many more under construction.

There seemed to be only two snags – one economic, the other navigational; but both, everyone predicted, would soon be adjusted to. First, by the nature of the system, there were Mohowatt stations in isolated places with thousands of megawatts running to waste because output at the two ends of any couple was equal; so there was a certain amount of economic disturbance as new productive enterprises mushroomed in unsuitable areas. Second, magnetic compasses became unreliable without constant reference to the latest magnetic variation charts, which a hastily set up UN service had to publish monthly; somehow, the strange electrical events which were being provoked in the belly of Mother Earth were making her magnetic field unprecedentedly turbulent.

Still, these were small problems compared with the golden prospect of a twenty-first century of unlimited power – which pleased, among others, environmentalists who were unhappy about nuclear power stations and geologists with a gloomy eye on dwindling oil and coal deposits.

Professor Bernard Arklow, of the International Seismological Centre at Newbury, Berkshire, worried about neither of these. In fact he worried about very little, being completely wrapped up in his own subject; the standing joke among his more worldly wise colleagues was that old Arklow's ivory tower was the only known structure which would stand up even to his own beloved earthquakes.

He was all the more surprised, therefore, when the outer world impinged on him abruptly. He had been becoming increasingly excited by the implications of certain statistics, from the seismologists of the world, which it was his happy function to collate; and when the time came to prepare his annual departmental report for the year 2002-3, ready to communicate his provisional conclusions, in his usual scholarly preamble to that report.

Translated into everyday language, those conclusion were that over the past year increasingly abnormal movements and correspondingly abnormal stresses had been arising in the handful of giant plates which composed the Earth's crust. These stresses would continue to build up, the Professor convincingly showed, and would produce seismic phenomena – in short, earthquakes – not only along the classic earthquake zones where the edges of the plates met but within the area of each plate itself.

When he had completed and submitted his report, the Professor sat back contentedly. He looked forward to its inclusion in the Centre's overall report and to the impact it would have on his fellow-specialists. They would be furious at not having realized it first," but on the facts, they would be obliged to admit he was right.

No one could have been more astonished than the Professor when, three days after the typescript had left his desk, he received a summons to Whitehall – from a very high personage indeed.

He returned to Newbury the following day looking, for once in his life, subdued.

PART ONE

Nemesis

'My dear General,' the Permanent Secretary said impatiently, 'it's no good looking to the Prime Minister. He hasn't the remotest idea of the seriousness of the situation. As long as the balance of payments is improving -which it is at the moment, for a combination of seasonal and one-off reasons – he can concentrate on the things that matter to him. Exploiting differences within his own Party to his own advantage, and scoring points off the Opposition.'

There was silence between the four of them for a while. Down Whitehall Big Ben boomed the three-quarters. As its echoes sank into the murmur of the traffic beyond the tall windows, General Mullard shook his head. 'It's a terrifying thought, Harley, that the Government of our country…'

Harley snorted. 'I am tempted to reply, with Shaw's Undershaft: "I am the Government of your country." Or to be more accurate, we. The Civil Service – and don't imagine for a moment that I speak only for the Treasury…'

'I don't,' the General said drily.

'Quite. The Civil Service, the Services, industry, and the TUC. Of which we four – let's be frank about it -are the key minds in the key positions.'

'I doubt if ICI would agree with you about me,' Lord Stayne laughed.

'Come off it, Joe,' the TUC man said. 'ICI know the facts of life, whatever they wish they were. When you pipe, they dance – especially if I'm playing the drum. Same with the General here. He's not the top brass but he's the key brass. Thompson's a figurehead. No, Harley's right. So let's talk about realities.'

'Thank you, Sir Walter,' Harley nodded. 'And if – or rather, when – Situation Beehive arises, those realities will become even sharper.'

There was another brief silence, which General Mullard broke with the question: 'How long?'

'One month, six months – the seismologists can't be sure. They're all agreed that Professor Arklow's deductions are correct. The facts are no longer in dispute. Only the time factor is.'

'And the magnitude?'

'Only roughly predictable. But serious enough for the Official Secrets Act, with trimmings, to have been clapped on the Newbury staff as soon as the Professor set the cat among the pigeons.'