Its claws missed Gabby, and ripped into the side of the metal tank. Dark liquid spurted out over the dying creature, soaking the other Krillitanes too.

At once they started to shriek. Their skin began to smoke and blister. Gabby screeched in sudden pain.

'Krillitane Oil,' Henry realised. 'That tank is full of it!'

The oil was pooling on the floor. It spread out across the concrete, running in rivers towards the Doctor and Henry.

It was running towards the other Krillitanes too. The last of the ma.s.sive creatures seemed not to mind, but the original Krillitanes back away in fear.

Only Sir Manning and Miss Sark dared to attack again.

They flew at the last Super-Krillitane, shrieking in anger. They drove the creature back with the force of their attack.

Finally, the huge Super-Krillitane fell. It collapsed to the floor like a tree being felled. For a moment it lay, staring across at the Doctor and Henry. Its mouth twisted into what might have been a sad smile.

'Sorry about all the trouble,' it said in a weak voice. 'I'd run for it if I were you.'

Sir Manning stood over the fallen body. 'Yes, run, Doctor.

Run from the might of the Krillitanes.'

'Er, no, actually,' the dying creature said politely. Its voice was weak and frail, and it raised a ma.s.sive clawed hand. 'I meant run from the fire.'

Miss Sark and Sir Manning were about to attack again.

They froze, standing over the creature. Krillitane Oil from the leaking tank pooled round the dying Super-Krillitane.

'What fire?' Miss Sark said.

The large red Super-Krillitane gave a great sigh as it died. Its raised arm crashed down. Its claws hammered into the concrete floor, sending up a shower of sparks.

The Krillitane Oil caught fire at once. A wave of flame rolled across the floor, and Krillitanes exploded as it touched them.

The Krillitane that had been Clive managed to get high into the air, above the flames. Then the storage tank exploded in the heat, and Clive the Krillitane was engulfed in the fireball.

The Doctor and Henry ran, their arms over their heads to try to ward off the heat. Henry was choking on the black, smoky fumes.

'This way!' the Doctor yelled.

A dark shape reared up in front of them. Even in her Krillitane form, the Doctor could tell it was Gabby.

The fire rushed towards her. A wall of flame flared up between Gabby and the Doctor and Henry.

'Help me!' Krillitane Gabby shrieked. She backed away from the fire.

Henry started forwards, but the Doctor grabbed his arm.

'There's no way through. I'm sorry.' He raised his voice, so that Gabby could hear him through the fire. 'I'm so sorry.'

The Doctor walked quickly away.

Henry waited a moment, but there really was nothing he could do. He turned away, and followed the Doctor.

Chapter Fourteen.

Together, Henry and the Doctor watched from the road nearby as the factory burned. Soon fire engines arrived, then an ambulance. The Doctor and Henry both knew they would find no one and nothing alive inside.

'Well done, Henry,' the Doctor said. 'They really did misjudge you.'

Henry shook his head. 'I never wanted this.' He pointed to the fire, which was still burning brightly.

'Nor did I,' the Doctor said. 'All that effort. They were so clever. So misguided. They actually created new life, a whole new race...' He shook his head sadly. 'Such a waste. Could have been worse though,' he decided.

'Really?'

'Oh yes. You and I could have been burned to a crisp.'

Henry laughed. 'I suppose so. I guess my job's gone up in smoke as well as the factory, though.'

'I guess so,' the Doctor agreed. 'Your pension's OK, though. I fixed that for you in the main computer.'

'I still need a job.' A thought occurred to Henry. 'You're not hiring, I suppose?'

The Doctor smiled sadly. 'Well, I do have a vacancy. I'm not looking for anyone to fill it just now, though, thanks all the same.'

'Pity.'

They walked slowly away down the road. Henry could feel the heat of the fire on his back.

'You'll think of something,' the Doctor said.

'I already have. I'm going to talk to James Purcell. He's a big shareholder in lots of other firms, and he knows about the Krillitanes. He saw them, after all. Maybe he can fix me up with something.'

'I'm sure he can,' the Doctor said. 'After all, you did save his life. Thanks for everything, Henry. You were brilliant. Just brilliant. If you need a reference, I'm your man.'

'Is the internet back to normal, do you think?' Henry asked.

The Doctor thought for a moment. 'I don't think you can really call the internet "normal", but yes as close as it ever gets. Thank to you. Henry. Thanks to you.'

It was a lovely sunny day. The last time the Doctor had walked along this street he was worrying about the internet.

Now he knew it was fine. The strange virus the TARDIS had detected was the Krillitane code. Henry had sorted that out.

He had closed the Brainy_Crisps website and shut down all the firm's computers. The Doctor had helped Henry delete all the alien code. All the crisps had been withdrawn from shops for vague health and safety reasons.

The Doctor stood outside the TARDIS and looked round.

Yes, it really was a lovely day, but it was time to be going. He had journeys to make, adventures to get on with.

He was about to unlock the TARDIS door, when a boy hurried past. The boy was about 12 years old and had untidy black hair. It was Spike, one of the boys that the Doctor had seen playing football. He was eating a bag of crisps.

The Doctor smiled as he remembered how the boy had explained to him about Einstein. 'Are those crisps any good?'

the Doctor asked. 'How would you rate them on a scale of one to ten? Please take into account the taste value of each crisp and bear in mind the nasty effects of too much salt and fat. What do you think?'

The boy stared at the Doctor, his mouth open in surprise at the question. A crisp was half in and half out. The boy crunched up the crisp, still staring.

'Well?' the Doctor prompted.

In answer, the boy blew the loudest, longest raspberry the Doctor had heard for centuries. Then he laughed and ran off.

The Doctor grinned. Just as he had hoped, everything was back to normal. He unlocked the TARDIS and went inside.

A few moments later, the street was empty.