Prologue

The TARDIS was spinning through the vortex.

In the control room, the Doctor was working at the console. Nita was standing nearby. Michelle was on the other side of the console. The monitor showed an Okudagram of a subspace radio wave.

"I've identified the signal. It's from a Time Capsule, which was reported missing in this sector seventy-five years ago."

Nita looked at the monitor. "It's in distress."

"I'll bring us out of the vortex."

The TARDIS was suddenly rocked and the alert status went to mauve.

"We've entered a massive gravitational field."

"There are no stars or other stellar bodies listed on our navigational charts. However, sensors indicate the presence of an extremely strong gravitational source in this vicinity. Michelle, can you localize the source of the gravity field?"

Michelle worked the console.

The viewscreen displayed a starfield with a large dark ball at the centre. At this distance, it appeared as smooth as a billiard ball, but because it was so dark it was hard to discern anything else. Everyone was mystified by this strange object.

"Sensors?"

"I'm having difficulty scanning the object. However, it would appear to be approximately two hundred million kilometers in diameter."

Nita reacted with astonishment. "That's nearly the size of Earth's obit around the sun."

"I wonder why we didn't detect it before now? Ah…the object's enormous mass is causing a great deal of gravimetric interference. That might have prevented our sensors from detecting the object before we dropped out of the vortex."

They all looked at this strange object on the screen. Suddenly, a look of wonder came across the Doctor's face…he might have found something hitherto only imagined. "Could this be a… Dyson Sphere? It does fit the general parameters of Dyson's theory."

"A Dyson Sphere?"

"It's a very old theory, Love. I'm surprised you haven't heard of it. A twentieth century physicist, Freeman Dyson, postulated that an enormous hollow sphere could be constructed around a star. This would have the advantage of harnessing all the radiant energy of the star. A population living on the interior surface would therefore have a virtually inexhaustible source of power."

"Are you saying there might be people living in there?"

"Possibly a great number of people, Nita. The interior surface area of a sphere this size would be equivalent to more than two hundred fifty million planets."

"Doctor, I have located the distress signal. It is coming from a point on the northern hemisphere."

The Doctor thought for a moment. "I'll take us into a synchronous orbit above that position."

The TARDIS materialized near the Sphere. At this range, the monstrous object looked like a giant wall in space, which stretched into the distance. Where before, the sphere appeared perfectly smooth, they could now make out intricate patterns on the surface suggesting construction supports, but again they were too far away to make out anything distinct.

They were holding relative position at thirty thousand kilometres above the surface.

The Doctor was looking at the console. "I have found the Time Capsule. It has impacted on the surface of the sphere. There are no life signs. However, there are several small power emanations… and life support is still functioning at minimal levels."

Nita looked to the Doctor, who thought for a moment… then nodded. They needed to go down there.

The TARDIS materialized inside the time capsule and the Doctor, Nita, Michelle and Carolyn stepped out. They immediately began to look around.

The time capsule had made a crash landing on the surface of the sphere. There was some damage visible, but not so much that the ship would be incapable of later flight.

The control room was fairly small with a modest console in the middle. The ship's technology and design was noticeably older than the TARDIS and reflected outdated engineering methods and philosophy.

The lights were dim and there didn't seem to be any equipment working at present. One or two of the panels on the console were damaged or burnt out, and the roundels looked smashed and broken.

Nita reacted to the smell. "The air's pretty stale."

The Doctor looked at his sonic screwdriver. "Life support is barely operating."

Nita turned to Michelle. "Would you please see if you can increase the oxygen level?"

Michelle nodded and moved to one part of the console.

The Doctor's sonic led him over to the materialization panel. "Nita."

Nita moved over to take a look.

"The materializer is still online… it's being fed power from the auxiliary systems."

Nita looked at the console. "The rematerialization subroutine has been disabled."

"That's not all… the phase inducers are connected to the emitter array… the override in completely gone… and the pattern buffer's been locked into a continuous diagnostic cycle."

"This doesn't make any sense… locking the unit in a diagnostic mode just sends inert matter through the pattern buffer. Why would anyone want to –"

The Doctor suddenly saw something on the console. "There's a pattern still in the buffer."

Nita, shocked, looked at the console. "It's completely intact… less than point zero zero three percent signal degradation. How is that possible?"

"I don't know… but I've never seen a materialization system jury-rigged like this."

They both looked at the monitor for a shocked moment.

"Could someone… survive in a materialization buffer for seventy-five years?"

"I know a way to find out."

Nita thought for a moment… then nodded. The Doctor worked the console for a moment… then activated a final control…

The Time Capsule shimmered, the time rotor pumped up and down once, then a figure began to materialize, and finally solidified in front of a shocked Nita and Doctor.

"Jamie!"