Jacko's giant figure was immersed in a flood of uniforms and, on the landing above, Wright struggled with two men who were trying to take the rifle from him. With six hands on the stock, the barrel sawed this way and that until finally there was a sharp explosion and a shower of plaster plummeted down from the ceiling on to the policemen battling in the hall below. At the same time, Wright and his adversaries, taken by surprise by the shot, lurched against the elegant eighteenth-century balustrading guarding the gallery and crashed through it. There was a splintering crunch, and a thump which shook the timbers of the old house as the three men landed. One of the policemen was knocked cold by the impact. As the other staggered groggily to his feet, Wright leaped for the wall and grabbed for one of a pair of crossed sabres displayed over the stone fireplace.

The THRUSH man whirled, murder in his glaring eyes — and that was when Ernie Bosustow acted. Darting in under the gleaming blade, he dropped the shotgun, hacked viciously at Wright's shin, planted a useful left in the pit of the baronet's stomach as he jerked up a leg in involuntary agony, and then locked his fingers together and brought down his doubled hands on the man's neck as he doubled up, retching for breath. The next moment, Curnow and a tall constable were snapping the handcuffs on his wrists.

Jacko rose from the mêlée by the drawing room door like a balloon dragging at its moorings. With a roar of rage, he fought free of all his attackers. He picked up a beefy sergeant, lifted the heavy policeman above his head and pitched him bodily at the others. As they fell in a tangled heap to the ground, he shook his great head — and found himself face to face with April.

The girl didn't hesitate. Drawing back her right arm as far as it would go, she hit him — a long, looping, roundhouse blow that came up from the floor and buried itself with all her weight behind it in his solar plexus.

The giant stared at her unbelievingly, the breath whooping from his savaged diaphragm. Slowly he folded up — and then the police were on him again. And this time they had his hands behind his back and the handcuffs locked before he could draw one agonised breath.

"All right then," Curnow panted, straightening his tie and glaring at Wright. "Let's get the formalities over with, for a start. I must—"

"No, no." It was April who interrupted. "Mark — he's got Mark tied up in some cave with a booby trap bomb designed to blow up the station on the Tor. We must get him out first.. .

"Go ahead and get him out," Wright said venomously. "The door's not locked. Be my guest."

"Since we've got you anyway," Curnow began, "I'm in a position to say that, if you assist the forces of law and —"

"Law and poppycock! I'm saying nothing. You have..." he consulted his wrist watch "... exactly thirty-one minutes, Miss Dancer. And the best of luck to you."

The superintendent sighed heavily. "I think he means it, too," he said grimly. "Looks as though it may be up to you, young Bosustow, after all."

"I'll do what I can — but how did you get here anyway? What in the name of... How did you all get here? And why?" There was blank astonishment in the boy's voice.

"Have you forgotten already? You were carryin' on about it enough! You were being tailed, boy. We've had men on you for days. You know that."

"You mean... out in those seas... you followed in another boat? You sailed into the Keg-'ole? You found your way down those passages?" There was stark disbelief in Ernie's voice.

Curnow nodded. "When we follow someone, we follow. And there's others but you can handle a boat, others but you were in school at Porthallow and messed about down here as kids. Some of 'em maybe in the Force."

"So I did hear voices," April said. "But we're wasting time. Come on!"

As she seized the boy's arm and led him to the door, she heard the policeman say: "There's a boat out, down in the cove. Ready to launch. A nice freshly painted boat in a strange reddish-orange colour. Would it be yours?"

"Of course it's mine," Wright sneered. "I have a licence for it, too. I demand an explanation for this unwarrantable intrusion, this insufferable—"

"That's all I wanted to know... Gerald Everard Wright, I am a police officer engaged in enquiries into the deaths of Sheila Duncan and Harry Bosustow. I have reason to believe that you may be able to help the police in their enquiries and I must ask you…

But the girl was outside the front door, running, running for the stables and the thicket which concealed the entry to the passageway leading to the chamber where Mark Slate was held a prisoner.

Bosustow found the place immediately; he led her unerringly down a maze of tunnels and corridors in the rock, stumbling over stones, sliding on the damp patches, lurching against projections in the wan light of a torch whose battery was almost spent. But fourteen more minutes had passed before they stood before the oak door leading to the chamber, for it must have been all of half a mile in a straight line from Wright's house to the main mast of the secret station.

Sobbing for breath, April stood outside the door and stared at the thread of light outlining it. At least Mark wasn't in the dark, she thought.

"Mark," she croaked. "Mark? it's April — are you all right?"

"April! Don't for God's sake come in! Don't touch the door." The voice was tight with anxiety, the voice of a man dragged back from a journey from which there was no return.

"All right, Mark..."

"No, you don't understand. There's some kind of infernal machine wired to the door; it'll go up the moment you

"I know, Mark. I know, Listen, we've got to get you out... Tell me: can you see the door on your side?"

"Very nicely, thank you."

"How is the booby trap fixed? Is it a wire attached to the handle? Could we maybe saw through a different part of the door without tripping it? Is it a circuit that gets broken? Is it a contact? Can you see if —"

"It's none of those," Slate's voice cut across her, stronger now. "There's a trembler coil. The slightest move would You don't have to open the door. If you leaned hard on it, or rattled the handle…"

"What's in the chamber, Mark?"

"Me."

"Mark, this isn't the time... What else?"

"A great number of sticks of dynamite, a quantity of nitro glycerine in drums, a huge Victorian hour glass connected to an electrical complex that looks like the inside of a computer, a bulb hanging on its flex, and that's all!"

"There's no other entrance, no other door?" Her voice was taut with despair.

"You want jam on it, don't you, lovey?" Mark Slate said.

"How's the air in there, Mr. Slate?" Ernie Bosustow asked suddenly.

"Hallo! That sounds like our lighthouseman… Nice and fresh, thank you, if that helps... Oh. I see what you mean... Yes. There is a grating. Rather an old one set in distinctly ropey-looking cement, high up in the wall. You don't think...?" The voice was suddenly tinged with a trace of hope.

"We haven't time to think. We must go," Ernie yelled. "See you."

"I don't want to be a bore," the imprisoned man called, and there was a break in his voice, "but... the sand is pretty low. How much time is there left?"

The girl looked at her watch and caught her breath. "Eleven minutes."

"Eleven minutes. Oh... well, the best of Cornish luck to you."