Cawdale circled, half a dozen pairs of binoculars on the bridge focused upon the fog. When they had first sailed through the patch it had been roughly six miles long; now it was less than a mile in length. Freddy Box caught his breath. For a split second he had seen something in the water, but before he could be certain what it was the lookout buzzed the bridge.

  ‘Ship’s boat, sir. Bearing green two zero.’

  Now they could all see the boat quite clearly. Was it the one they had run down? Through his glasses Hope could not see any sign of damage to the boat; nor was there anything to indicate that it was occupied. He raised his glasses to study the fog and found he could see right through it. Even as he watched, the last few thin wisps were blown away by the wind, and the surface of the sea was clear.

  ‘Surely that boat isn’t what we’ve been searching for— what the whole Navy’s been searching for, sir?’ Freddy Box was plainly bewildered.

  Hope was equally puzzled. He was wondering whether the lucky fluke of Cawdale ramming the boat had been responsible for the dispersal of the fog? But where was the ship the boat belonged to? Maybe they’d be able to get a lead from the boat. ‘We’ll secure that boat, Number One.’

  ‘Aye, aye, sir.*

  When Cawdale bore down to within a hundred yards of the ship’s boat, the boat blew up. The enormous explosion shattered the boat into fragments, hurling a fountain of greenish-white water and splintered wood more than a hundred feet into the air. Hope, his ears-still ringing, turned to Box. ‘Get the sea boat away, Number One,’ he ordered. ‘See what there is to salvage.’

  There wouldn’t be much left, but the experts might find the bits interesting.

  20

  Warburton had a long conversation with Garrett by radio. ‘We are in your hands, Doctor,’ the Prime Minister said. ‘At the most we have a week. Unless we can stop the radioactivity increasing within that time, we are doomed. Without that E.U.H.F. set of yours we can’t do it.’ He told Garrett of the incident during Cawdale’s search. ‘It looks as though we are on the right track, don’t you think?’

  ‘It would seem so, sir.’

  ‘Well, you know what you have to do, my boy. May God be with you!’

  When the conversation was finished, Garrett sat back to think over the things he had been told. It was going to complicate matters to have more than one transmitter working at the same time, particularly if they were working on the same frequency. He might waste an awful lot of time—more than could be spared—tracking down boats and rafts instead of the parent ship or ships.

  His hosts had supplied him with pipe and tobacco and he enjoyed the rare luxury of a smoke. The job to be tackled was one that had to be done correctly the first time; there would be no second opportunity. If he failed to find the enemy transmitter within seven days, he would still keep on searching, but his interest would be purely academic by that time.

  It would be at least three hours before the E.U.H.F. set was installed in a Sunderland flying-boat. He went to see Mary, but she was still unconscious. The doctor who was in charge of her case was hopeful.

  ‘She needs rest more than anything.’

  Garrett smiled wryly to himself at the words. Rest was what they all needed more than anything; but there was no prospect of any… except permanent rest. It was too grim a thought to pursue, and he went off to be introduced to the crew he would fly with. The most experienced men on the station had been assigned to the job. They seemed to him to be incredibly young, and he was somewhat annoyed by the courteous deference they showed him.

  ‘Anybody’d think I was their blasted grandfather!’ he muttered fiercely to himself.

  At last all the preparations were completed, and the flying-boat was ready for take-off. As the Sunderland climbed from the water, Garrett opened his eyes and found the fresh-cheeked radio operator sitting opposite and grinning at him. Garrett glared at him and tried to pretend that he had merely been dozing. The scientist busied himself with getting the E.U.H.F. set into action.

  For ten minutes after he had switched on the generators and oscillograph, Garrett waited for the equipment to warm up. The Service personnel had made a good job of the installation. The temporary switchboard was within easy reach of where he was sitting. At a pinch he could operate the whole thing single-handed.

  Garrett bracketed for a maximum on the cathode-ray tube, moving the tiny aerials of the E.U.H.F. set backwards and forwards, and reading the bearings from a scale each time the picture on the C.R.T. was at its maximum. He cut in the reflector, and the picture increased still further. The results were excellent. He had been afraid that there would be a great deal of interference, but the radio mechanics had seen to that. The shielding they had fitted was more than adequate.

  The navigator, Flight Lieutenant Calder, was watching him closely, jotting down the bearings as the Doctor called them out. When Garrett had given more than a dozen readings, Calder added them up and produced the average figure. He looked enquiringly at the scientist, who nodded. Calder made a rapid calculation, then drew a thick red line across the map on the navigating table.

  ‘Set course two nine six degrees,’ he ordered the pilot.

  The Sunderland banked, then levelled out. ‘On course two nine six degrees,’ the pilot reported back.

  Calder raised a thumb at the Doctor. ‘We’ll check again in ten minutes, sir.’

  Each check showed only a small error from the original reading, and the navigator was content to keep the Sunderland on the same course.

  It was almost dawn when they passed out of the pall through which they had flown for hours. Garrett spent five minutes in the astrodome, gazing at the fading stars. The navigator tugged at the scientist’s borrowed flying jacket.

  ‘Another quarter of an hour, sir, and we’ll be in the search area.*

  They maintained the same course, with Garrett taking a reading every minute. The signals were getting even stronger, so that he had to turn down their volume to stop the set from being swamped. They were flying at twelve thousand feet, and beneath them was an unbroken carpet of cloud. Once again Garrett took a reading.

  ‘We’ve overshot!’

  The signal’s bearing was one hundred and eighty degrees off their line of flight. The navigator gave new instructions to the pilot and the Sunderland banked to fly back over its previous course. Garrett kept the E.U.H.F. set working constantly, calling out his readings to the navigator. Suddenly the bearings reversed themselves again. Once more they had flown over the enemy transmitter. The scientist rubbed his hands in satisfaction. The job had been easier than he had anticipated.

  Wing Commander Robert Stavely, the pilot, called him up over the intercom. ‘Shall I go downstairs to have a closer look, sir?’

  ‘Is it safe?’ The instructions from Whitehall were that absolutely no risks were to be taken.

  ‘I’ll move out twenty miles, sir, before I go downstairs. We should be perfectly safe at that range.’ Stavely took the aircraft rather more than the distance he had stated before he started to lose height. In a gentle glide, the flying-boat dropped towards the white-gold carpet of cloud. The beauty of the scene, after the weeks he had spent in semi-darkness, made a lump rise in his throat.

  At one thousand feet they came out of cloud. Below, the sea was a sullen grey, its colour almost matching the clouds. The second pilot, Flight Lieutenant Harold Greening, pointed through the perspex. ‘Look at that!’ They were headed towards a bank of cloud or fog that stretched straight down to the surface of the water.

  When Stavely passed the information back to Garrett, the scientist nodded happily. ‘Fly round it,’ he ordered the pilot. ‘I want to know how big it is. And at the same time keep an eye open for the Navy. They must be somewhere around.’

  They flew round the bank of fog, keeping about three miles from its outer edge. Garrett checked his readings every few seconds. There could be no doubt at all: the transmission was coming from somewhere inside the fog bank. Twice Stavely circled the fog. Although they had been keeping watch for any sign of the fleet, so far they had not raised a single ship. Garrett was just about to tell the navigator the latest bearing when, without warning, the pattern disappeared from the cathode-ray tube, leaving only a straight line of time base.

  Garrett swore under his breath. ‘That would happen!’ he said to the navigator. ‘I thought it was all going too smoothly.’ Quickly he checked the circuits in the oscillograph. Everything was in order, and the E.U.H.F. set was working correctly. There was but one answer: the unknown transmitter had gone off the air.

  Was it because of the flying-boat’s presence? Did the people operating the enemy transmitter know that they had been traced? Or was there some other reason? If they had stopped because the flying-boat was in the vicinity, would the enemy start up again if the Sunderland flew away? It was worth a trial. He explained to Stavely.

  ‘O.K., sir, we’ll push off and see if we can come up with the Navy,’ Stavely replied. He spoke to Calder. ‘You got a good fix, Tom?’

  Calder drew a red circle on the talc covering the navigating table. ‘Got it pinned down to the yard, Skipper.’

  ‘Right. We’ll go and tell the boys in navy blue all about it.’

  Flying just below cloud level, the Sunderland droned off on its search for the ships that were somewhere in the area. Half an hour later they were challenged by a scouting destroyer, then passing on they came in sight of the main fleet. The crew of the aircraft counted forty-five ships; battleships, aircraft-carriers, cruisers and destroyers. The flying-boat C for Charlie circled the fleet, reporting what had transpired to the flagship by Aldis lamp.

  As Garrett idly twiddled the knobs of the T/R the well-known trellis-work pattern reappeared on the cathode-ray tube of the oscillograph. The enemy was transmitting again. Garrett checked his watch. The unknown transmitter had been off the air for nearly forty minutes. He had assumed that they would have to start transmitting again within a few minutes, and his guess had been proved correct.

  His guess had been based on the previous break in transmission. On that occasion the enemy had been off the air for twenty minutes; presumably as the result of an accident. It seemed very probable that the break in transmission had been caused by a flying-boat carrying away some part of the aerial array. At least, that was the construction the Prime Minister had placed upon the evidence, and Garrett saw no reason to doubt it.

  He brought the signal strength up to a suitable level, then took several readings, calling them out to Calder to note down. The navigator looked across at him. ‘Give me some more readings, sir,’ he shouted. Garrett complied, but the look of surprise on Calder’s face grew more pronounced.

  ‘Is your box of tricks set up right, sir?’

  ‘Is something wrong?’

  ‘Something screwy somewhere. The bearings aren’t the same at all.’ He held up his plotting chart for the scientist to see. The site of the enemy transmitter must have moved a considerable distance since they took the first set of readings, according to the latest markings. The enemy must be steaming away from the fleet at full speed. C for Charlie passed this latest information to the flagship, then set off to pinpoint the transmitter.

  The readings on the T/R were just as consistent as before. Garrett wondered how long the enemy would be able to keep transmitting before he was forced to close down again. As Jong as the unknown transmitter kept at work, it would be easy to locate it. But if they stayed off the air for too long, would that have some effect on the fall of snow over Britain? Probably the enemy had to keep transmitting if he wanted the snowfall to continue unbroken. Garrett smiled grimly. The game was nearly over.

  Calder was working anxiously over his slide-rule, jotting down his findings and drawing lines across the talc covering his plotting table. He leaned across to Garrett. ‘Look, sir, do you think there can be two transmitters? Because it doesn’t seem possible that we’re tracking the same one. The plots are miles apart!’

  The same doubt now gripped the scientist. According to the navigator’s calculations, the enemy transmitter must be moving at well over forty miles an hour! It was not until C for Charlie flew over the source of transmission that the scientist was able to appreciate fully what had happened. Since they had first circled the transmitter, ninety minutes had elapsed. And in that time, if the navigator’s figures were to be believed, the unknown craft had moved one hundred and five miles! It was beyond the bounds of possibility that a ship could move through open water at such a speed. There must be two transmitters.

  The pall of fog they were circling looked about the same as the former one; it looked about the same size, and there was no other way in which it could be distinguished. The only difference was that the top of the fog bank was well below the cloud ceiling, which was now more than five thousand feet. The weather was changing, the cloud becoming broken in places, with the sun glinting on the water here and there.

  The pilot called him over the intercom.

  ‘What do we do now, sir?’

  Garrett eased his aching body into a more comfortable position. ‘Keep circling. I’ve got to work this out.’

  ‘We shall have to start for home in three hours,’ the pilot answered to Garrett’s query.

  ‘Three hours, eh? Thank you.’ Garrett scratched his chin. The nearest ships were more than five hours away. By themselves, the naval vessels would not be able to track down the enemy. Somehow or other the Sunderland would have to stay on the scene. ‘Tell me, Wing Commander, can you land this thing on the open water?’ He repeated the question. ‘Yes, 1 mean could you put her down on the water here?’

  Stavely hesitated. ‘It’s not my favourite form of relaxation, sir.’

  ‘But you could do it? Without killing us all, I mean?’ ‘Maybe, sir; maybe not. I’ll have a try if it’s necessary.’ ‘Good man. Could you get her into the air again?’ ‘Thousand to one against it, Doctor.’

  ‘Hm!’ The odds were too great to be risked. What the devil should he do? The responsibility was so great that he could hardly think. Whatever he decided, it must be the right thing. There wasn’t time to make mistakes. Even if he didn’t make a mistake, would there be time to do what had to be done? With only the one T/R, could he track down the pair of enemy transmitters so that both of them could be destroyed before the deadline? Deadline. The word was grimly appropriate.

  Certainly it was hopeless even to contemplate returning in the Sunderland for refuelling. He looked across at the navigator. ‘How fast is that fog bank moving?’

  ‘Six to seven knots, I reckon.’

  Garrett moved to the side of the fuselage and looked out through the observation window at the bank of grey mist. What was hidden behind that facade? Was it a large ship? Or was it something little larger than a rowing boat? Or were there several ships? Suddenly the trellis-work pattern on the C.R.T. collapsed. The transmitter in the fog bank had gone off the air. Hastily he turned the tiny dipole aerials of the E.U.H.F. set, searching to find out whether the other transmitter had taken over.

  Sure enough, the signal was building up again; this time from a completely different bearing. He called out a series of readings for Calder.

  The navigator groaned. ‘We must be surrounded by the ruddy things!’ he said. ‘This is another on?.*

  Garrett’s heart missed a beat. He slumped back in momentary despair. With two transmitters the task had been formidable: with three transmitters it became almost impossible. ‘Are you sure?’ He knew the answer before the navigator spoke.

  ‘Positive, sir.’ He held out the plotting chart. ‘Look.’ The new position was more than a hundred miles from where they were. ‘Isn’t that new plot near the fleet’s position?’

  ‘About fifteen or twenty miles away, at a guess.’

  The scientist stared at the chart. If the ships were diverted to the new target, they would reach it within an hour. C for Charlie could also be on the scene well under the hour. The prospect of immediate action was better than having to wait for hours. Up to the present they had been keeping radio silence; now there was no point in continuing it.

  Admiral Crowther read the signal flimsy. The message from C for Charlie was brief and concise. Crowther rubbed at his chin with the back of his right thumb, then issued a string of orders. Half the fleet continued to steam ahead, but the other half, in response to his instructions, changed course and headed towards the position given by the flying-boat, Crowther’s flagship changing course with the others. If there was a likelihood of immediate action, Crowther had no intention of missing it.

  C for Charlie was circling overhead by the time the flagship came up with the fog bank. Garrett reported to the Admiral that signals were coming from inside the fog.

  ‘I don’t expect them to keep transmitting for long,’ Garrett’s message continued. ‘If they follow the same scheme as before, this transmitter will close down any minute now, and the transmission will be taken up by another set.’

  Crowther scratched at his chin again. The fog bank in front of his ships was at least five miles wide. If any ships were hiding in it, the chances were that they’d be somewhere near the middle. Well, it was no time to play games. The stakes were tremendous; therefore he’d have to take risks that no sailor in his right mind would even contemplate.

  He had twenty ships with him and he was going to use them all. As he explained his plan to the other officers on the battleship’s bridge, he saw their faces flinch. The plan was quite simple. The ships were to form up in line abreast and to steam through the middle of the fog, at twenty-five knots; each ship keeping station with the one on its starboard side. If there were powerful naval units hidden in the fog, his plan could lead to the loss of many of his own ships. If the enemy vessels were small, then even a destroyer could hope to survive a collision.

  The manoeuvre to bring the men-of-war into line abreast was carried out with Review precision. With every ship in position, speed was brought up to twenty-five knots; with all hands at action stations, the fleet tore through the grey water towards the greyer mist.