Their labours had revealed new details. The carven figure of a woman could faintly be discerned on the central stone disc, a priestess with hands cupped in front of her. And the delicate tesserae of the mosaic showed a spiralling drift of winged creatures travelling from the outer rim of the mosaic towards the central figure.

The Priestess stood silently observing their work. When Khassian and Orial drew near, she looked at Orial from beneath her veils.

‘A flight of dragonflies,’ she said.

Khassian thought he glimpsed them exchange a secret smile.

‘Are you ready, Jolaine?’ Orial called softly.

‘Just one thing more.’

Jolaine Tradescar leaned over the carved figure and pressed one half of an enamel disc into her cupped hands. Philemot produced the other half and slotted it into place so that the two halves became one whole: a perfect lotos.

A deep vibration shuddered through the Hall: the floor trembled beneath their feet.

‘Earthquake!’ someone shouted in panic.

‘Earthquake be damned!’ Jolaine Tradescar shouted back. ‘This is Lifhendil engineering. It’s a mechanism.’

Khassian glanced anxiously at Orial. Suppose her miraculous resurrection was but a temporary reprieve – suppose, like the dragonflies, she would be reborn for a brief while to fulfil her task, and then die?

The Priestess raised her hands for silence.

Orial began to sing in her quiet, pure treble and as the musicians matched their voices to hers, a hush fell amongst the murmuring onlookers who were gathering outside the candlelit hall.

Orial’s voice faded. She was swaying on her feet.

Jerame sprang forwards, catching her as she fell.

‘This must stop,’ he cried. ‘She’s too weak. She can’t sustain it. The strain on her heart –’

‘No, Papa.’ Orial struggled up again, ‘It must work. It will work.’

‘The circle,’ Jolaine Tradescar called. ‘Make a circle, Orial. Remember the wall-painting?’

Orial slowly, unsteadily moved forward, beckoning the musicians to join her.

‘A circle!’ Khassian struck his forehead with his hand, ‘It doesn’t work as a chant. It’s a round. I can hear it. I can hear how it fits together. Watch me – I’ll bring you in.’

He peered tensely at the other musicians. Then he took in a breath and began to sing. The ancient, wordless chant echoed in the darkness, each note husky but true. He caught Valentan’s eye and at his signal, Valentan joined the round. The two voices wound around each other, Valentan’s ringing tenor against Khassian’s baritone. And now the Priests had begun to understand the musical sense of it – they added their voices. Khassian nodded to Azare and he took counter-tenor, adding a third part to the round.

Orial was watching Amaru, her whole body taut, waiting to enter with the treble.

Khassian brought her in with a movement of the hand and her voice became a filament of sound snaking its way through the others, thin, high and pure.