Prologue
The Doctor, Sarah Jane Smith and Harry Sullivan watched from the terrace as the monster slowly sank beneath the surface of the Thames.
"Where's it going?" asked Sarah.
"Oh, it's on its way home, no doubt," the Doctor replied.
"Home? Where?" said Harry.
"Loch Ness, Harry – after all, that's the only home it knows," answered the Doctor.
As they turned to leave the terrace, Sarah couldn't help wishing the monster a safe journey. It wasn't evil in itself – it had only obeyed its masters. Soon the old stories would be true at last. There really would be a monster in Loch Ness.
20 years later...
The scout ship orbited the small, rocky planet known as Sol 3. Its job was to survey the planet and, if possible, discover what had happened to the previous scout ship. Its last communication stated that the planet was suitable for invasion, but that had been 20 years ago by the small planet's standards. The scout ship scanned the planet for any threat, but found none.
The crew should have scanned the space behind them. A small asteroid came tumbling out of space, heading towards the scout ship, setting off the proximity alarm, but by then it was too late. The asteroid slammed into the scout ship, the impact knocking the ship's crew unconscious and causing the ship to lose its orbit. The asteroid continued on its long voyage throughout the depths of space while the scout ship now hurtled towards the tiny blue planet. The ship soon hit the planet's outer atmosphere, but luckily its heat shields were still operational. The ship continued on its collision course, flying over continents, countries and cities. Many of the planet's inhabitants saw the blazing ball of fire and pointed up at it, wondering what it was.
Minutes later, the scout ship finally hit the ground in a remote part of the planet, a lake in the country called Scotland, to be precise. The depth of the lake stopped any evidence of the crash from reaching the surface, but the inhabitants of the lake did notice. They inspected it, but found it uninteresting, and let it lie there in the small crater it had made. The ship's computer systems had shut down for now, and had already put its crew into suspended animation.
Several days later, the main power control bleeped into life. It had detected a strange radiation coming from the old castle next to the lake. Slowly, the computer drew on that radiation to make repairs to the scout ship, and to eventually revive its alien crew...
Author Note: I added the opening scene with the 4th Doctor, Harry Sullivan and Sarah Jane as part of my current revision. The scene is taken from a novelisaion of a classic Doctor Who story.