The Curse of the Gloamglozer by Paul Stewart, Chris Riddell

rock was exactly the same as the flight-rocks which kept the fleets of sky ships aloft, and even the small buoyant-rock of the cage. Except for its immense size.
    Wilken Wordspool's lesson at the Fountain House school came back to him. What was it he'd said? Ah, yes. The outer rock was not as solid as it seemed, but was hollow, translucent. At its centre was the hard rock. Red. Glowing … What had Wordspool called it? Quint frowned.
    ‘ Heartrock ,’ he murmured. That was it. Solid, permanent, and home to the treasury – the safest, most secret place in all of Sanctaphrax. Around it was … Quint shivered as the word came to him. There was the stonecomb .
    The stonecomb – a vast network of cavities like wood-bee honeycomb – surrounded the heartrock. Alive, growing all the time, ever-changing, it was this stonecomb that gave the rock its buoyancy. But it was a terrible place, the old sky-scholar had warned the class. A place of terrors. A maze that changed behind you each time you took a step forward. Sky-scholars don't go there , Wilken had intoned solemnly.
    And why would one want to? Quint had thought at the time. Yet, here he was, freezing cold and staring glumly at an entrance into what must be the dreaded stonecomb. Was he mad? He stamped his feet. The chain gave an ominous clang. More to the point, was the Most High Academe mad?
    ‘If only I could go back to bed,’ he whispered, his thick breath pouring from his lips. But the professor had been clear in his instructions. Quint was to wait for him to return. He was not to move.
    The Great Hall bell chimed three hours.
    The snow had by now stopped falling. Quint's hands and feet were numb. His temples throbbed. If it hadn't been for the burning lamp, he might have frozen solid. His thoughts had wandered so far, he was no longer thinking of anything at all. It was as if – like some of the hibernating creatures from the least hospitable depths of the Deepwoods – his body and mind had been switched off.
    Quint didn't notice the bell chime four hours. He didn't register the flickering light in the tunnel, or hear the sound of approaching footsteps. It was only when the professor appeared before him, kicking the drifted snow away from the ledge as he emerged, that Quint stirred. He blinked once, twice. His long cold wait was finally over.
    ‘Professor,’ he said. ‘Am I glad to see you. I was beginning to worry that …’ He paused. Even by the flickering shadowy light cast by his failing lamp, it was clear that something was wrong. Ashen-faced and trembling, Linius looked dazed, drained. ‘Professor?’ Quint asked gently.
    ‘Over … it's all over,’ Linius Pallitax rasped. His voice, like his face, seemed to have aged during the time he'd been gone.
    Quint unlatched the door and helped the professor back inside the cage. As the light from the cage-lamp fell across his face, Quint gasped and recoiled with horror. Linius's mouth was pinched, his expression desperate and his skin bore the waxy pallor of the dead. His eyes – usually so animated – stared straight ahead, dull andunseeing. They registered nothing – neither his surroundings, nor Quint's helpless concern.

    Quint knew he had to get the professor back to the Palace of Shadows as quickly as possible and get help. Tweezel would know what to do. Welma would have potions and medicines, he was sure. And Maris would …Quint winced. Maris! What would Maris say? He could only hope that she did not blame him, Quint, for her father's condition.
    Quint tried to think clearly. He must move fast, but carefully. He knew he could not simply turn the winch handle once the hook and tolley-ropes had been released. It could jam or even sever the chain. No, before he went up, he would have to go down further, to dislodge any frozen blockage around the pulley wheels. With the buoyant-rock ice cold and straining to rise, that would be difficult.
    ‘You can do it,’ he muttered to himself through clenched teeth