6

The Heligan Structure was shuddering constantly now, as if the ancient tree were trying to shake off all the elegant wooden buildings that had been attached to it. The groaning of the thicker branches as they heaved and thrashed had a tuneless music, like the bellowing of huge animals. And down through it all Ven led the Doctor, hiding now and then from passing spores, down past the chamber where the TARDIS was embowered, to deep places where even he had never been.

‘It is forbidden to go any further,’ he warned, peering down the last passage that led into the root ball. Cobwebs hung like curtains, stirring softly in a wind that seemed to come from the heart of the tree. A faint, silvery light showed at the far end.

‘Oh well, rules are made to be broken!’ said the Doctor cheerfully, and then, seeing how afraid the boy was, added, ‘All right, you stay here. Shout if any of those spores come poking about, eh?’

He went on alone, using his hat to sweep aside the cobwebs. The light grew brighter. He emerged into a space whose walls and floor and roof were made of ancient, interwoven roots. Tangled among the roots was machinery torn from the guts of an old starship; one of those twenty-fourth-century computers with the big dials and buttons, controlling the flow of chemicals through the Heligan’s boughs. Wires and coloured flexes led from the machines, wrapped around the roots like strands of ivy leading up into the ceiling. The Doctor followed them, looking up into the shadows above his head.

Among the twistings and knottings of the wood, two eyes were watching him.

‘Ah!’ said the Doctor. ‘Director Sprawn, I presume?’

He could make out a face around the eyes now, ancient, mutated, scarcely human, sprouting twigs and tendrils like a carving of the Green Man in a country church. There were the suggestions of a body, spreadeagled on the ceiling, almost engulfed in the web of roots. So that was how Sprawn had made sure the Heligan would do his bidding, even after all these years. He had become a part of it.

They barred the doors, but the spores burst through them. They piled up benches, but the spores shoved those easily aside. And then it was all fright and confusion and the hack and thrust of spears, the screams of the people snatched by the spores, the shouts of their comrades as they fought to tear them free, the squeals of children hiding behind their mothers at the far side of the hall. And Aggie and Leela sap-spattered, fighting side by side, spear and knife and desperate courage against the spines and tendrils of the spores …

‘So, Doctor!’ growled the face in the ceiling, root-muffled. ‘We meet again!’

‘Well, we’re meeting for the first time, technically, Sprawn,’ said the Doctor, looking quickly around at the machinery. ‘Though we will meet again, nine hundred years in the past. Your past: my future. That’s the trouble with time travel, you never know whether you’re coming or going …’

He reached over and turned one of the knobs on the nearest control panel. It seemed to do nothing but draw an angry hiss from the face above him.

‘The Heligan will tear itself apart rather than let you escape, Doctor! We shall be avenged at last for what you did to us all those centuries ago!’

The Doctor nibbled a fingernail, his eyes still on the controls. Absent-mindedly he said, ‘Ah yes, about that. I can just about accept that I might, one day, in a moment of weakness, wear a bow tie, but there is no way I will ever take up arms against anyone unless they thoroughly deserve it. I don’t think you and your fellow colonists on Golrandonvar were innocent victims of the Thara rebellion at all. I think you were vicious tyrants.’

‘The Thara were vermin!’ shouted the face in the ceiling. ‘They opposed every improvement we tried to make to their benighted world!’

‘Improvements like altering their atmosphere?’

‘Golrandonvar had to be terraformed: turned into a world fit for people, not those methane-breathing swamp-monkeys. We had no choice but to exterminate them!’

‘Now that’s a word I’ve never liked,’ said the Doctor, starting to sound quite stern. ‘I can see why my future self is going to help them to get rid of you. Just as I’m going to have to help your own people now, to save them from your suicidal rage.’

‘Let them die!’ screamed the mad face above him. ‘What have they to live for? For nine hundred years they’ve scraped a living in this wretched weed, imprisoned by your moralistic meddling!’

‘Wretched?’ asked the Doctor. He tried another dial, and chuckled delightedly when it produced a beeping noise and a bubbling of amber fluid in a glass container buried deep among the roots. ‘Oh, I think they’ve done rather well with the place, all things considered. They’re ready to move on. Except you didn’t exactly play fair with them, did you? This tree should have had offspring, a forest of Heligans that would have made the world below us habitable. But you didn’t want that. If they’d had a new world to build, your descendants might have forgotten all about their vengeance. So you made some changes to the genome, didn’t you? Stopped the Heligan producing spores at all, until now …’

‘Doctor!’ There were scrabbling sounds from the passage outside. Ven came hurrying in, bearded with cobwebs, still scared of the forbidden chamber, but more scared of what was outside it. ‘There are spores coming!’

‘I have called them here to kill you, Doctor,’ said the head in the ceiling, and it began to laugh. Saliva pattered on the brim of the Doctor’s hat.

‘And that’s another thing,’ the Doctor said, while his hands went spidering over the controls and the machinery beeped and burped. ‘Heligan spores aren’t normally aggressive. You must have tampered with the chemical messages that control their behaviour …’

‘Doctor!’ Ven fled to the far end of the chamber as the first spore came pushing its way along the passage, reaching out with woody limbs.

‘It’s all right, Ven,’ said the Doctor. ‘The only things that Heligan spores naturally attack are parasites that threaten their parent tree. Now I’ve adjusted the chemical balance, they should start to behave normally again …’

The spore reached past the Doctor. Its tendrils took hold of the roots that formed the wall. It climbed awkwardly, like a land crab. Other spores entered, and also started climbing. The thing that had been Director Sprawn watched, wide-eyed. He tried to struggle free of the ceiling, but his limbs were roots, his flesh was wood, the stuff of the tree was woven through him. He shrieked as the spores clustered around him. Stone-hard root-tips rose and fell like axes, hacking and hewing, splattering thick sap. The shrieks did not last long.

‘What are they doing to him?’ asked Ven.

‘He’s being pruned,’ said the Doctor. ‘Cut out …’ He felt sorry for Sprawn. In many ways it was a wonderful achievement, this great tree that he’d created. If only he had been able to enjoy it for what it was, instead of poisoning it with his need for vengeance.

‘Will the Heligan be all right without him?’ asked Ven.

‘Oh, I should think so,’ said the Doctor.

Some of the spores had now turned their attention to the machinery, driving their roots through the old computer casings, ripping out spaghetti-tangles of electronic innards in fountains of dazzling sparks. Blinking away the after-images of the explosions, the Doctor started to lead Ven back up the passageway towards the outer branches and the others.

‘In fact,’ he said, ‘I should think it will be a great deal better off …’

In the Hall of Justice the spores had stopped attacking all at once, suddenly going still, as if they had forgotten what they were supposed to be doing – or remembered.

‘It’s the Doctor!’ said Leela, wiping the sap from her knife as she turned to the others. ‘He’s done it!’

Her comrades were not so sure. They watched warily, holding their spears ready. When the spores all suddenly shuffled into life again a few moments later, they leaped hastily back behind their barricades of piled-up benches.

But the spores were not returning to the attack. Ignoring the humans, they rustled their way to the hall’s huge, misty windows. The cellulose tore as they leaned their spiny shapes hard against it. They clustered on the windowsills, tensing their many legs, and then, one by one, they sprang out, releasing jets of pent-up gas to help thrust themselves free of the Heligan’s gravity.

‘There!’ said the Doctor, sauntering in with his hands in his pockets, Ven close behind him. ‘Look at that! Another ten years or so and that world we’re orbiting should start to be quite habitable.’

‘Ten years, Doctor?’ The Justiciar turned to look at him. She still felt faintly that she was failing in her duty by not making him stand trial, but so much had happened since his arrival, so much had changed … ‘What shall we do in the meantime?’ she asked.

‘Oh, you should branch out!’ the Doctor said with a grin. ‘Think about advertising this place. A tree of this size, surrounded by its own floating forest – it must be one of the wonders of the galaxy! You should try luring tourists instead of Time Lords …’

From every window of the Heligan Structure now the spores were taking flight, unfurling their first young branches as they spread across the sky. The humans stood wonderstruck, gazing at the airborne forest that they had seeded. Ven took Aggie’s hand. The Doctor tapped Leela on the shoulder and nodded towards the door.

‘So,’ the Doctor asked, a while later, when they had managed to cut a way through the woody stems to the door of the TARDIS. ‘Seen enough trees for a bit?’

‘I do not care if I never see another,’ said Leela.

‘Excellent! Because I was thinking the sand-reefs of Phenostris IV might be worth a look. I haven’t been there since …’

The door closed behind them. After a few moments, the TARDIS slowly dematerialised, leaving a TARDIS-shaped cage of branches to mark the place where it had stood. The noise of its going echoed and re-echoed through the passageways and chambers of the Heartwood, but there was nobody to hear it. All the people of the Heligan Structure were crowding at its windows, watching as the skies of the world below them filled with newborn trees.