Professor Slocombe peered over the pen-besmirched, match-riddled map with profound interest. At length he leant back in his chair and stared a goodly while into space.

“Well?” asked John, who had been shifting from one foot to the other for what seemed like an age. “Has Pooley found it?”

The Professor pulled himself from his chair and crossed the room to one of his bookcases. Easing out an overlarge tome, he returned with it to his desk. “Undoubtedly,” he said, in a toneless voice. “If you will pardon my professional pride, I might say I am a little miffed. I have sought the pattern for weeks and you find it in a couple of hours.”

“I think we had the natural edge,” said Omally.

Pooley, whose injured parts were now beginning to pain him like the very devil, lay slumped in an armchair, a hand clasping the neck of the whisky decanter. “I only hope that it will help,” he said. “Those lads are on to us, and I escaped death by a mere hairbreadth this night.”

“We have by no means reached a solution,” said the Professor, in a leaden tone. “But we are on the way.”

Omally peered over the old man’s shoulders as he leafed through his great book. “What are you looking for now?”

“This book is the Brentford Land Register,” the Professor explained. “The pubs you have plotted were all built during the last one hundred years. It will be instructive to learn what existed upon the sites prior to their construction.”

“Ah,” said John, “I think I follow your line of thought.”

“I think my right elbow is fractured,” said Jim Pooley.

The Professor thumbed over several pages. “Yes,” he said. “Here we have it. The Four Horsemen, built upon the site of the cattle trough and village hand pump.” He turned several more pages. “The New Inn, upon this site there has been a coaching house for several hundred years, it has always boasted an excellent cellar and a natural water supply. Built in 1898, the North Star, a significant name you will agree, founded upon Brentford’s deepest freshwater well.” The Professor slammed the book shut. “I need not continue,” he said, “I think the point is clearly made.”

“My collarbone is gone in at least three places,” said Jim.

“It can’t be the water supply,” said Omally. “That is ludicrous. Aliens do not steer themselves through space guided by the village waterworks. Anyway, every house in Brentford has water, every house in the country, surely?”

“You fail to grasp it,” said the Professor. “What we have here is a carefully guided natural watercourse, with the accompanying electrical field which all underground water naturally carries, culminating in a series of node points. The node points channel the ley earth-forces through the system, terminating at the Flying Swan. If you will look upon the map you will see that the Swan is built exactly one third up from the Thames base line of the Brentford Triangle. Exactly the same position as the King’s Chamber in the Great Pyramid. A very powerful position indeed.”

“It all appears to me a little over-circuitous,” said Omally. “Why not simply stick up a row of landing lights? If these Cerean lads have all the wits that you attribute to them, surely they could tamper with the National Grid and form a dirty big cross of lighted areas across half of Britain?”

“Possibly,” the Professor replied, “they might be able to do that for an hour, possibly for a day, but this pattern has been glowing into space for a hundred years, unnoticed by man and untouched. It is reinforced by the structures built above it, pubs, thriving pubs. This is Brentford; nobody ever knocks down a pub here.”

“True,” said Omally. “We have little truck with iconoclasts hereabouts.”

“This beacon could go on radiating energy for a thousand years. After all, the Cereans had no idea how long they would have to wait to be rescued.”

“There is definitely evidence of a cracked rib here,” said Pooley, feeling at his chest.

“All is surely lost,” said Omally.

“I didn’t say it was terminal,” Pooley replied. “Just a job for a skilled surgeon or two.”

Professor Slocombe stroked his chin. “At this very moment,” he said, “somewhere on the outer rim of the galaxy, the Cerean Strike Force is heading towards its homeworld. Finding none, it will inevitably be turning here, guided by the descendants of its stranded forebears. Unless otherwise diverted or destroyed, they will home in upon their landing area, and I do not believe that we can expect any of that ‘We bring greetings from a distant star’ benign cosmic super-race attitude to be very much in evidence upon their arrival. We must work at this thing; I do not believe that it is without solution.”

“My ankle’s gone,” grizzled Pooley. “I shall walk with a limp for the rest of my life.”

“Do put a sock in it, Pooley,” said the Professor.

“But I’m wounded,” said the wounded Pooley. “Somebody might show a little compassion.”

“I don’t think you realize the gravity of the situation.”

“On the contrary,” said Jim, waggling a right wrist which was quite obviously a job for the fracture clinic. “I’ve never missed an episode of ‘The Outer Limits’ – true, I’ve been in the bog during many a title sequence, or slept through the last five minutes, but I know what I’m talking about. None of this smacks to me of sound science fiction. All this sort of stuff does not occur in the shadow of the gasworks. Alien invaders, who we all know to be green in colour and pictured accurately upon the front page of the Eagle, do not muck about with council water supplies or conveniently arrange for the location of public drinking-houses. I take this opportunity to voice my opinion and pooh pooh the whole idea. There is a poultice wanting upon these knees and more than one of my fillings has come adrift.”

“An uncle of mine has connections with the Provos,” said Omally. “If you will sanction the exemption of the Swan, I might arrange for the levelling of every other relevant pub in Brentford.”

Professor Slocombe smiled ruefully. “That, I think, might be a little too extreme,” he said. “I am sure that a less drastic solution can be found.”

“Nobody ever listens to me,” said Jim, going into a sulk.

“As I see it,” said Professor Slocombe, “the Flying Swan is the epicentre of the entire configuration. It has been so aligned as to act as the focal point. The harnessed Earth forces flow through the alignment and culminate therein. There must be something located either within the Swan or beneath it into which the energy flows. Something acting as locative centre or communicating beacon to these beings. As to what it is, I have not the slightest idea.”

“Maybe it’s the darts team,” said Pooley. “We’ve held the shield for five years. Perhaps your lads have infiltrated the team and are guiding their mates in through a series of pre-planned double tops.”

“You are not being obstructive are you, Jim?” the Professor asked.

“What, me? With the collapsed lung and the damaged cerebral cortex? Perish the thought.” Pooley took up his glass in a grazed fist and refilled it.

“Now we know where it is,” said the Professor, “it surely cannot be that difficult to find it.”

“But what are we looking for?” asked Omally. “You find a great triangle, we find the constellation of the Plough.”

“I find it,” said Pooley.

“Pooley finds it,” said Omally, “one thing leads to another, but we just go around in circles. What are we looking for?”

“I think I can make a reasonable guess,” said Professor Slocombe. “We are looking for something which is the product of a high technology. Something which utilizes the vast power fed into it and acts as the ultimate homing beacon. It must have been placed in the Swan during the last year or so, for it was only during this time that the Earthbound Cereans gained knowledge of their prodigals’ return and wished to announce their own presence.”