'No!' roared the Mara. 'Destroy that crystal. It will prevent my Becoming!'

Dugdale lumbered forward and grabbed at the crystal around the Doctor's throat - but the moment he touched it, a surge of energy threw him across the cave.

Lon flung himself upon the Doctor.

The Doctor dodged, ran to the carving of the Great Snake, and reached up to take the Great Crystal from its socket. He couldn't move it.

The Great Crystal seemed fixed in place as if magnetised by the energy-flow.

The Doctor tugged in vain.

Lon flung himself upon the Doctor's back, trying to drag him away.

The Doctor tightened his grip on the Great Crystal -and their combined weights pulled it free.

As it came out of the socket, the Mara serpent gave one last terrible scream.

The colossal Snake slumped to the floor. Instantly it began to decay, as if time had been speeded up.

The disintegrating Snake writhed and hissed and steamed, body-fluids spurting. In a matter of seconds, it was a rotting ma.s.s of carrion.

On the hill above the Cave of the Snake, Dojjen rose from his sitting position, and moved slowly away. His work was done.

The Doctor found Tegan, a blessedly normal Tegan, sitting hunched on the edge of the dais. She was white-faced and trembling but her eyes were clear, and the mark of the Mara was gone from her arm. The Doctor went and sat beside her.

She looked up at him and sobbed, 'It was awful.

Awful!'

The Doctor put a comforting arm around her shoulders. 'It's all right now, Tegan. It's all over.'

'You don't understand, Doctor. The feelings of hate and rage ... It was terrible. I wanted to destroy everything.'

Awkwardly the Doctor patted her shoulder. 'I know.

But you're free of it now.'

'Has it really gone - forever?'

The Doctor looked at the pile of putrefying snake flesh in the centre of the cave. 'Yes. The Mara has been destroved.'

He looked round the cave. People everywhere were slowly recovering, staring wildly at each other, too astonished to speak. The Doctor saw Ambril picking up the Great Crystal, and restoring it lovingly to the wooden chest. He saw Lon still dazed, with Lady Tanha cradling his head in her lap. Chela was rubbing his eyes, staring around him in astonishment. They could all take up their lives again, thought the Doctor. Ma.n.u.ssa was free at last of the menace of Mara.

He felt too tired for explanations and thanks and congratulations. Best to slip away now. Let the Ma.n.u.ssans make what sense they could of their terrifying escape. They could invent another ceremony.

The Doctor took Tegan by the arm, collected a still-dazed Nyssa, and led them out of the Cave, down the steps, and through the deserted market quarter towards the TARDIS.

Despite his exhaustion the Doctor felt strangely at peace.

In his mind's eye, he could see Dojjen striding away into the hills. The old man turned and waved in farewell.