"Bad news, Doctor," the operator said. "Flash in from Brandon Hall about a friend of yours, Andrew Symington. Apparently the emergency intelligence unit in the Admiralty bunkers were attacked yesterday. Marshall and three of the others were shot."

Maitland gripped the strap over his head. "Andrew? Is he dead?"

"No, they don't think so. His body hasn't been found, anyway. Marshall managed to get an alert through before he died. The gunmen were working for someone called Hardoon. As far as I could make out he's supposed to have a private army operating from a secret base somewhere in the Guildford area."

"I've run into Hardoon before," Maitland cut in. " Marshall was also working for him." Quickly he recounted his discovery of the crates of paramilitary equipment in Marshall 's warehouse, the uniformed guards. "Hardoon must have decided to get rid of Marshall; probably he'd outlived his usefulness." He looked up at the strap in his hand, and jerked it roughly. "What the hell could have happened to Symington, though?"

Halliday lowered his head doubtfully. "Well, maybe he's O.K.," he said, managing a show of sympathy. "It's hard to say."

"Don't worry," Maitland said confidently. "Symington's a top electronics and communications man, far more valuable to Hardoon now than a TV mogul like Marshall. If his body wasn't found in the bunker he must still be alive. Hardoon's men wouldn't waste time carrying a corpse around." He paused, listening to the hail drive across the roof. "All those crates were labeled ' Hardoon Tower.' This secret base must be there."

Halliday shook his head. "Never heard of it. Though the name Hardoon is familiar. What is he, a political big shot?"

"Shipping and hotel magnate," Maitland told him. "Something of a power-crazy eccentric. ' Hardoon Tower '-God knows where, though."

"Sounds like a hotel," Halliday commented. "If it is, it won't be standing, that's for sure. Sorry about your friend, but as you say, he'll probably be O.K. there."

Maitland nodded, leaning on the radio set and searching his mind for where Hardoon Tower might be. He noticed the radio operator watching him pensively, was about to turn away and rejoin the trio at the rear of the compartment when the man said:

"The Hardoon place is just near here, sir. About ten miles away, at Leatherhead."

Maitland turned back. "Are you sure?"

"Well, I can't be certain," the operator said. "But we get a lot of interference from a station operating from Leatherhead. It's using a scrambled vhf beam, definitely not a government installation."

"Could be anyone, though," Maitland said. "Weather station, police unit, some VIP outfit."

The operator shook his head. "I don't think so, sir. They were trying to identify it back at Brandon Hall; there was even an MI5 signals expert there. I heard him refer to Hardoon."

Maitland turned to Halliday. "What about it, Captain? He's probably right. We could make a small detour out to Leatherhead."

Halliday shook his head curtly. "Sorry, Maitland. I'd like to, but our reserve tank only holds two hundred gallons, barely enough to get us back."

"Then what about uncoupling the rear section?" Maitland asked. "It's no damn use anyway."

"Maybe not. But what are we supposed to do, even if we find this character Hardoon? Put him under arrest?"

Halliday returned to the periscope, indicating that their argument was closed, and hunched over the eyepiece, scanning the road. Maitland stood behind him, undecided, watching the radio-compass beam on the navigator's screen. They followed the beam carefully, driving along a razor edge between a stream of dots-leftward error-and a stream of dashes-rightward error. At present they were deliberately three degrees off course, in order to take advantage of the motorway's firm foundations. Halliday was following a bend in the road, and the radio compass rotated steadily, from 145° to 150°, and then on around to 160°. Unoccupied for the moment, the operator was searching the waveband of the vhf set. He picked up a blurred staccato signal and gestured to Maitland.

"That's the Hardoon signal, sir."

Maitland nodded. He stepped over to the operator as if to hear the scrambled signal more clearly, and slowly eased his torch out of his hip pocket, clasping the heavy cylinder with its steel-encased reflector firmly in his right hand. He edged between the operator and the compass, which was still revolving. When he was satisfied that the operator would no longer remember the precise bearing, he raised the torch and with a quick backhand stroke tapped in the glass screen.

Quickly he began to hammer away at the set, smashing in the compass and plunging the torch into the valve-crammed cabinet. Shouting to Halliday, the operator struggled to his feet and tried to pull Maitland away. Then Halliday swung back from the periscope and flung his arms around Maitland's shoulders. The three men wrestled together, their blows muffled by the swaying vehicle and their heavy clothing, then fell to the floor.

As they struggled onto their knees, the tractor, still following the circular course Halliday had been giving to the driver, tipped over sharply as it left the roadway and ran rapidly down the incline.

Halliday pulled Maitland to his feet, his face thick with anger. Lanyon had joined them, and helped the radio operator to rise. The corporal stumbled over to the set and stared blankly at the wrecked console, his fingers numbly tracing the ragged outlines of the compass.

He looked wildly at Halliday. "The set's a write-off, Captain, a total wreck! God knows what our bearing was! We were moving around that bend. I wasn't watching it."

Halliday wrenched at Maitland's jacket. "You damn fool! Do you realize we're completely lost?"

Maitland shook himself free. "No you're not, Captain. I hate to force your hand, but it was the only way. Look."

He reached across to the vhf set and turned up the volume, so that the staccato gabble of the mysterious station sounded out into the compartment over the noise of the wind beating against the tractor. With one hand he rotated the set in its bearings until, at an angle of 45° to the lateral axis of the tractor, it was at maximum strength.

"Our new direction beam. Follow that and it should take us straight to Hardoon Tower."

"How can you be sure?" Halliday snapped. "It could be anything!"

Maitland shrugged. "Maybe, but it's our only chance." He turned to Lanyon, quickly explained what had happened to Andrew Symington.

Lanyon pondered this for a few minutes, then turned to Halliday, who was peering through the periscope.

"Seems as if we've no alternative, Captain. As it's only a few miles away, a short detour won't hurt us. And there's always the chance that if this fellow Hardoon is planning some sort of takeover when the wind blows out, we may be able to anticipate him."

Halliday clenched his fists, scowling angrily, then nodded and swung back to the periscope.

Five minutes later they reversed onto the highway and moved off down a side road toward Leatherhead, following the vfh signal. Maitland had expected that they would have difficulty in locating Hardoon Tower, but Halliday soon noticed something that confirmed his suspicions about Hardoon.

"Take a look for yourself," Halliday said. "This road has been used regularly all through the last four or five weeks. There's even wire mesh laid down at the exposed corners."

Lanyon took the periscope, confirmed this with a nod. "Heavy tracked vehicles," he commented. "Must have been carrying some really big loads." Grinning, he added: "Looks as if Pat may get a story after all."

They followed the signal, steadily increasing in strength, toward the Hardoon estates at Leatherhead, as much guided by signs of recent activity along the road as by the radio beam, the wind pushing them on at a steady 25 mph.