Dyspepsia and Spookie found out what the pit wheel was for.

There was a mineshaft connecting all levels of the complex—and it went down a very long way. In the mineshaft was a cage hanging from a cable which went over the pit wheel, just like in a coal mine. An ordinary elevator would have taken an hour to get to the bottom. But a pit cage got there in a minute.

They put on hard hats and got in the cage. Everywhere you went in Ashbrooke you could hear a slight rumbling sound. But, once inside the cage, it got much louder.

The cage started to go down, slowly at first. It passed a landing without stopping. “Level 1. Storage area. Nothing to see here.”

The cage went down a bit further. “Level 2,” said the Prof. “Here we’re 20 m below ground zero. The main accommodation is here. It’s where you’ll be staying tonight.”

The big pit wheel turned again and they went down another level, 40 m deep.

“Level 3,” said the Prof. “Generators—just like you see in any power station. But instead of three or four, there’s hundreds here.”

Now, at last, the pit wheel let them drop like a stone. They dropped for over a minute until the wheel slowed the cage and they felt its floor pushing hard up at their legs.

“Level 4. We’re 600 m below ground zero. Twice the height of the Eiffel Tower. This is the lowest point of the complex—that is, the part of the complex that people have dug for themselves. The Earthspot has dug down a lot farther, of course. But this is where the control room is situated, because you need to get as close to the beast as safety allows, to see what’s going on. Right now, it’s 10 km below ground zero—and still going. Once it’s through the Earth’s mantle there’ll be no fetching it back. So we need to get a move on.”

By now the rumbling was extra-loud. As they stepped out of the cage they could feel the solid rock trembling beneath their feet. A tunnel led off into the distance. Its sides were rough and chipped, just as miners with pickaxes had left it. A line of dim lights trailed along the roof, each in its own little wire cage.

But they didn’t have to walk the whole length of the tunnel. There was a mini railway, just like in a theme park, but grubbier. They got in it and the motor started up with a whine. As the little yellow train trundled along, the rumbling grew louder and louder until they had to shout above it to make themselves heard. Dyspepsia felt the air quivering on her cheek.

The train stopped and they got out. There was a heavy round door like a walk-in bank vault. The Prof punched in a code, and the door swung open.

Once inside, the rumbling was much quieter. The control room was well-insulated for sound as well as heat. The officer at the master console stood up smartly and saluted. Dyspepsia knew he was saluting her, so she saluted back, as Lieutenant Blowhard had taught her how.

They climbed some iron steps with diamond-shaped holes. That brought them to a big wide window which sloped in at the bottom. Professor Schrodinger said that the glass in the window was half a metre thick. It needed to be that thick to withstand the steam pressure inside the well.

It was dark behind the window. But as Dyspepsia stood in front of it, twenty searchlights in the well behind were switched on.

What she saw nearly stopped her heart.

The control room was a blister sticking out into the well. At this depth below ground, the well was 15 m across—as wide as a street.

Directly opposite the window, a huge waterfall tumbled into the well. It spewed out of a tunnel in the rock as wide as the well itself, falling in a flurry of foam and spray. The searchlights made rainbows in the mist.

“Where’s all the water coming from?” said Dyspepsia.

“It’s coming from an adit—a sloping tunnel driven through solid rock right back to the seabed just off Hendon.”

“Why does it need all that water?”

“To cool the well down so it doesn’t turn into a volcano. This makes a lot of steam. The power company has been using that steam to work the generators at Level 3.”

“So that’s how the Earthspot makes free electricity for everyone!” said Dyspepsia.

“Now,” said the Prof, “watch this.”

He nodded to the officer at the console, and a watergate—a huge black half-cylinder—turned gradually, closing the adit. Soon the waterfall was shut off, leaving only jets of water spraying out at either end of the watergate.

The Prof said, “From here the waterfall drops over 150 m into the well, tumbling into the water that’s already there. That’s almost three times the height of Niagara Falls. It’s what makes the rumbling noise you hear all over Ashbrooke. As fast as we pour it in, the water turns into steam. Pretty big bathtub to fill, huh?”

Another nod from the Prof and the spotlights were turned off. But, in the well, it didn’t go completely dark. Dyspepsia and Spookie stared down into the boiling water far below.

It was glowing!

“That’s Hawking radiation!” said Spookie.

“Spot-on, Pookie. Percolating up through six miles of muddy water. Imagine how strong it is at the bottom.”

Spookie said, “Nothing gives off Hawking radiation except a mini black hole. How could I have made one—with a handful of Semtex? You have to squeeze a hundred tonnes into one Planck Distance to be sure of making one. Impossible!”

Impossible is not a word in Quantum Mechanics,” said the Prof. “Nothing is impossible. But some things are highly unlikely. Such as your making a black hole using Semtex.”

“So you reckon it quantum-tunnelled?”

“Quantum-tunnelling happens when you’re around, Pookie.”

Spookie stared downwards through the thick glass window. “It’s got a lot bigger since I saw it last.”

“It’s getting bigger all the time. It’s gobbling rock as it sinks through the Earth, melting a conical hole. At ground level it’s only a pinhole. But for every 40 m it goes down, the hole gets wider by a metre. So… six miles down—how wide is that?”

“A quarter of a kilometre,” said Spookie. It took her only a moment to do the sum in her head.

“And how much rock do you think it’s swallowed to make the well?”

Again it took Spookie only a moment to do the sum. “Roughly a billion tonnes.”

“You’re a smart cat, Pookie,” said Professor Schrodinger. “I always said so.”

“Why are the walls all black and shiny?” said Dyspepsia.

“Because the Earthspot is hot enough to turn the rock to obsidian. That’s volcanic glass, if you didn’t know.”

Something else caught Dyspepsia’s eye. Jutting out from just below the window was a gantry. It spanned the well and plunged into the wall above the watergate. Hanging from the gantry by a chain was something straight out of a horror movie.

“What’s that?” she said. “It looks like a robot lobster.”

“That’s a bathyscaphe—a pressurised vessel. We’re going to have to send Pookie ten kilometres down to the bottom of the well. That’s deeper than Challenger Deep: the deepest ocean rift on Earth. The water is boiling, so the vessel needs to be refrigerated. I call it the Cryo-Thermo-Bathyscaphe: CTB for short. Inside there are four cryo units—super refrigerators—and it’s protected outside by a cryomagnetic shield of my very own design.”

Dyspepsia said, “What’s all the gubbins hanging underneath?”

“Depth gauges; pressure gauges; black hole detectors. Plus a tokamak: a magnetic bottle. As you found out, an ordinary bottle can’t hold the Earthspot. There’s a big pair of pincers to grab hold of it and cram it in the tokamak. If that works, we’ve got a space rocket waiting for it in the USA. We’ll fly it back and launch it right out of the solar system, just like Voyager spacecraft. It’ll never comes back.”

“And if it doesn’t work?” said Spookie.

“Then you’ll have to try the other thing you see: a thermonuclear torpedo. That’s it, underneath everything else. It’s called a BFT-5. A magnificent weapon—it’ll take out a whole fleet of battleships.”

“How far away from the battleships are you supposed to be?”

“At least 80 km. Say 100.”

“And the well is only a quarter of a kilometre across at its widest?” said Spookie. She went very quiet.

Suddenly the officer at the console began to shout. “Sir! The Earthspot has begun to ascend. It will be up here in an hour!”

The Prof looked scared. “Pookie—it knows you’re here! If it reaches the surface, its radiation will waste the land from Edinburgh to York!”

“What can we do?” said Dyspepsia.

“You’ve got to talk to it, Pookie. Tell it to stay right there and you’ll come down to it.”

They gave Spookie a microphone. She shouted “Stay there, Earthspot. I’m coming down to you.” Her voice boomed in the huge chamber of the well and made the glass vibrate.

“…In twelve hours time,” prompted the Prof.

“…In twelve hours time!” shouted Spookie down the mike.

There was a long silence as everyone watched the dials on the console. Then the controller said, as if he could hardly believe it, “Sir! It’s going back down!”

“It heard you, Pookie,” exclaimed the Prof. “Start the countdown!”

Straightaway a metallic voice came over the public address system. “Earthspot minus 12 hours.”

Spookie swallowed hard. “I guess I’ve got to go down, now.”

…to be continued.