‘It’s not a spider this time,’ said Yaz.

  Mileva shuddered. ‘That sound …’

  The skittering was getting louder. There was a metallic tang to the sound that set their teeth on edge. A handful of people were hurrying away from it, glancing nervously behind.

  The black cloud rippled and shivered and solidified …

  ‘Rats,’ breathed Mileva, her hands clutching convulsively at the ledge. ‘A river of rats.’

  Now they could see she was right, as the torrent poured up the street towards them. Thousands of small dark bodies, with teeth chittering and sharp claws scratching stone. One man stood still in the middle of the street, a loaf of bread in his arms, his gaze fixed in horror at the oncoming sight.

  ‘Sir!’ the Doctor yelled down. ‘Run!’

  ‘Is he in danger?’ Yaz asked. ‘The spider didn’t hurt you.’

  ‘The readings on this are much higher! Please, sir – RUN!’

  The man turned to look up at them but he was already out of time. The river simply swallowed him up with a horrible, moist chewing and tearing.

  ‘Oh, God!’ Up on the second floor, Mileva covered her mouth, her eyes wide and horrified. Yaz turned away, sickened. The Doctor gripped the ledge, white-knuckled, her mouth a tight line, until it was all over – until the rats had passed down the street, leaving only a grisly twisted skeleton behind them. ‘I’m so sorry,’ she breathed.

  Then a plume of black smoke rose up from somewhere in the next street. The Doctor snapped into action. ‘Come on! We’ve got to follow it! Get downstairs as quick as you can!’

  Never had a cathedral been home to such great fear and so many pleading prayers. Everywhere Graham looked, adults clutched and rocked their silent children, faces raised to heaven, lips whispering endless Our Fathers. Candles flickered in every holder, casting shadows over already drawn faces, making them skull-like in the dimness. At the altar, the bishop was holding a service. Murmured prayers flitted across the stone-ribbed ceiling like sparrows. Further away from the Choir, it was harder to hear the service, not only because of the distance but because of other conversations, whispered and agitated, occasionally rising into a confrontation. ‘Why aren’t you doing anything?’ one man was repeating at a police officer stationed by a side chapel. ‘This is a national emergency, and you’re just standing there!’

  ‘I’m sorry, sir,’ the officer responded. ‘We’re just here to keep the peace.’

  ‘To watch our children die, more like,’ said the man furiously. Hands grabbed him and urged him away. Graham and Ryan breathed a sigh of relief as he capitulated. The officer looked down at the floor.

  ‘All these people …’ Graham said quietly, ‘and no one to help them.’

  ‘The Doctor will,’ said Ryan.

  ‘Yeah, but she’s not here, is she?’ Graham looked around. ‘I feel so useless.’

  A sudden flurry of activity by the main entrance distracted them. Six people were stumbling in, three children carried between them. The adults were all white-faced, their words clattering out of them: ‘Rats! Rats everywhere! Thousands of them!’

  Graham and Ryan made their way over. ‘What did you say?’ asked Ryan. ‘Rats?’

  A woman tugged on his jacket. ‘They chased us down the street!’ she said, her breath stinging his face. ‘My sister Aiga … she fell … and they … they ate her.’ She stopped, appalled at her own words. ‘They ate her,’ she repeated, bewildered – and then burst into tears.

  Ryan patted her awkwardly as Graham peered out into the empty square. ‘Where did you see these rats?’

  ‘They’ve gone now,’ one of the men said. In his arms he held a boy of about two, eyes closed, skin blue around the lips. ‘They were nearly on us, and then they just … I don’t know. Vanished. One minute they were there, the next they were gone.’

  ‘Like the spider,’ Graham said to Ryan.

  He nodded. ‘Only the rats killed someone.’ He and Graham helped the new arrivals find somewhere to settle on the end of a pew and then withdrew to a side aisle. ‘I need to do something; I’m going mad here. The Doctor told us to help.’

  ‘Help how, though?’ wondered Graham, pulling up the zip of his jacket. ‘It’s getting colder. These people could use some warming up. Blankets or something.’

  ‘Curtains – or them frocks the priests wear?’ said Ryan.

  ‘Good thinking. Maybe the bishop has a stash of biscuits somewhere. And there must be a water tap, we can make some drinks. Every little helps, right? Grab a candle. Let’s get to work.’

  The Doctor raced down the street, sonic held out like a divining rod. Mileva and Yaz followed along behind, turning right then left, left again, then …

  ‘Oh blast!’ The Doctor swung the sonic in a wide arc, trying to get a fix. ‘The signal’s disappeared! Too weak! Or too fast for us. One or the other. Maybe I can change the settings, try to expand the range.’ She bopped the sonic several times, which made a protesting noise.

  ‘What’s that?’ asked Yaz suddenly.

  ‘What’s what?’ asked Mileva.

  Yaz was staring at the wall of a nearby shop. Smooth grey stone – she ran her hand over it. ‘I saw something here, just for a sec, and then it … oh!’ She pulled back her hand in shock. ‘There’s something there. Invisible.’

  ‘Invisible?’ said the Doctor, immediately intrigued. She ran her hand over the surface. ‘You’re absolutely right, Yaz. There’s something here, stuck to the wall. Something … squidgy.’

  ‘I’m sure I saw it,’ said Yaz. ‘Just for a second, when you were waving the sonic around.’

  The Doctor directed the sonic at the wall. Clinging to the smooth stone was something small and star-shaped that pulsed and quivered with energy.

  ‘What in heaven’s name is that?’ asked Mileva. Her hand reached for the cross she wore around her neck.

  ‘I don’t know,’ said the Doctor, ‘but it’s beautiful. Look at the way the light ripples across its skin.’

  ‘It’s like a sort of starfish,’ said Yaz, gazing at it. ‘How come we can see it now?’

  The Doctor checked the settings on the sonic. ‘Ultraviolet. I must have switched it on by accident.’ She swung the beam away from the small creature, and it vanished. She swung it back, and the illuminated star reappeared. ‘It’s only visible in ultraviolet light.’

  Mileva stared at the sonic. ‘You can create ultraviolet light without a vapour lamp? What is that device?’

  ‘Oh, standard issue back at my lab,’ said the Doctor carelessly. She peered more closely at the creature. ‘What are you then, my squishy?’ She prodded it gently. ‘So light and soft, you can hardly feel it.’

  ‘Look!’ Mileva pointed as another starfish came floating gently through the air as though caught in a current, bumping into the stone, spiralling slowly to rest next to the first.

  ‘They can fly!’ Yaz was amazed. ‘How many are there?

  ‘There could be thousands,’ mused Mileva. ‘How would we know if we cannot see them? Perhaps they belong to an entire invisible realm, evolving alongside our own over millions of years.’

  ‘Or on another world. Look out!’ The Doctor took a step backwards as two more starfish came drifting through the air to settle beside the others. ‘I wonder what’s attracting them?’

  ‘And why use a colour beyond the visible spectrum?’ added Mileva. ‘Perhaps it is a kind of camouflage? To avoid predators? Or because they are predators?’

  The starfish pulsed in time with her words. Another one drifted down to join the little cluster.

  ‘They glow more when we talk,’ said the Doctor, fascinated. ‘Do they feed on words?’

  ‘Or thoughts,’ suggested Yaz.

  The Doctor let out a yelp that startled the others. ‘Yaz! You’re brilliant! Thoughts! Imaginative energy!’ She turned to Mileva. ‘Go on, have some more ideas. That beautiful mind of yours, working out what they could be.’

  Mileva looked puzzled. ‘I was merely speculating … we still know so little about the spectrum of light. For example, there are creatures under the sea that create their own light by phosphorescence. Phosphorescent materials absorb light and then emit it very slowly. It’s how radioactivity was discovered. I read all the papers on it.’ She became enthused. ‘It makes me wonder if we could find a way to transmit light waves through various solid objects, through changing the wave forms or …’

  ‘Look,’ whispered the Doctor. More and more starfish were floating towards them, so close they were bumping into each other on their way. ‘That’s it!’ She turned to Mileva. ‘You’re using your imagination. Every time you have an idea, more of them come. That’s what’s happening!’

  ‘Sounds like a children’s story.’ Yaz shook her head, wondering. ‘Magic starfish drawn to ideas?’

  ‘Children!’ exclaimed the Doctor, slapping her own forehead. ‘Yaz, you’re full of brilliant ideas today!’

  ‘I am?’ Yaz rubbed her eyes. ‘Not sure how. I’m knackered.’

  Mileva leaned against the wall, pressing her fingers to her temples. ‘I too. So tired, and my head aches.’ She slid down the wall to sit on the cold cobblestones. Yaz joined her. The Doctor crouched down, concerned. ‘You feel tired?’

  ‘Like lead,’ murmured Yaz.

  ‘Can’t … think any more …’ said Mileva, her eyes closing.

  ‘This explains EVERYTHING!’ the Doctor cried, jolting the other two awake again. ‘Well, not everything everything, but some of it. The starfish, and the children, and the energy readings …’ She switched settings on the sonic and pointed it at Mileva and Yaz. ‘Yes, the same thing! The energy is coming from humans – your imaginations! It’s being sucked out of you, by these tiny critters!’ She beamed.

  ‘That … doesn’t make me feel better,’ Yaz said, squeezing her eyes shut.

  ‘The starfish feed on imaginative energy,’ the Doctor went on. ‘And who has the most fertile imagination on the planet? Children. A new idea every ten seconds! Constantly questioning and wondering – a proper feast for a hungry magic starfish. No wonder the poor kids are all collapsing. Young minds can’t cope with so much energy being siphoned off.’ She frowned at the wall of glowing creatures. ‘We can’t have this, you know. You can’t just come in here and suck stuff out of people; it’s illegal. Those children are going to die if you don’t leave them alone.’

  ‘So tired …’ murmured Mileva.

  ‘Mileva?’ A voice made them all look up. Albert stood in the street, hair no longer carefully combed back, jacket collar ripped, arms hanging loosely at his sides. ‘My darling, is that you?’

  ‘Albert!’ With a sob, Mileva heaved herself to her feet and lurched into his arms. ‘I was so worried about you! What happened?’

  Albert held her for a moment and then put her gently away from him. ‘I found the rat,’ he said, his eyes taking on the feverish gleam they had seen before. ‘I found all the rats, Mileva! I told you I could hear them.’

  ‘Look at his hands,’ the Doctor said quietly to Yaz. ‘They’re trembling.’

  ‘They’re not normal rats, Mileva,’ Albert went on. ‘They’re twice the size. I think something has happened to them. They’ve evolved into killers. We have to tell people! We have to have the streets cleansed!’

  Mileva sagged. ‘Albert, no, not again …’

  The Doctor pointed the sonic at Einstein. ‘The readouts are off the scale!’ she said to Yaz. ‘The energy is just pouring out of him.’ She shone the ultraviolet beam on the wall. They both gasped. The wall was now completely covered with starfish, and they were pulsing brighter and faster than ever before.

  ‘It’s like he’s charging them up,’ said Yaz, astonished. ‘Like he’s some kind of human battery.’

  ‘That oversized parietal lobe of his! They’re getting the best feast of their lives,’ the Doctor agreed. ‘Trouble is—’

  ‘You don’t believe me!’ Albert said to Mileva. He took a step backwards. ‘You think I’m going mad, don’t you? I can see it in your eyes!’

  ‘I don’t know what to think!’ Mileva wailed. ‘All I know is, you’re not yourself.’

  ‘I’m not myself?’ Albert repeated. His eyebrows lowered and he stepped forward again. ‘What if you’re not yourself? What if you’re not who I thought you were, Mileva? Are you the sweet Dollie I used to write to, or are you someone else?’

  ‘Stop it, Albert, you’re frightening me!’

  The light emanating from the starfish began to darken into an intense fiery glow.

  ‘You never wanted to marry me,’ Albert said, his voice dropping to a menacing growl. ‘You just wanted to steal the ideas out of my head to further your own work.’

  Mileva gasped. ‘How can you say that? You know I love you more than my own life!’

  The skies were already gloomy with twilight; now an extra darkness settled around them; a whirling blackness. The Doctor looked up, alarmed. ‘Albert, stop it.’

  ‘What’s happening?’ asked Yaz.

  ‘The starfish don’t seem to make Albert tired,’ the Doctor told her. ‘If anything, he’s creating even more energy – but it’s damaging him. Like, I don’t know, an allergic reaction. It’s changing his personality – and all this extra energy is too much for the starfish to absorb, so it’s taking a darker path …’

  Behind Einstein the black cloud began to take shape: a tall, monstrous figure with a voluminous skirt, dark hair and a round face …

  ‘It’s Mileva,’ gulped Yaz.

  Mileva screamed in horror. ‘Albert, no!’

  ‘Albert, you have to stop!’ called the Doctor. ‘Can’t you see what your fears are creating?’

  Einstein turned around and quailed at the giant figure glaring down at him. ‘It’s not my fault! She’s in on it! Her, and my mother, and my colleagues at work! They’re all trying to destroy me!’ More giant figures started to form in the smoke, open angry mouths and reaching arms. A chimney pot was swiped from a nearby roof and smashed into the street, sending shards flying. The figures started to move closer, huge smoky shoes cracking the stones beneath their feet.

  ‘Doctor …’ said Yaz nervously.

  ‘Yes,’ said the Doctor. ‘That’s quite enough.’ She twisted the sonic again and pointed it directly at Einstein’s head. ‘Sorry.’ She pressed the button. Albert’s eyes rolled back in his head and he fainted clean away, folding onto the cobblestones like a marionette with its strings cut. Instantly, the looming figures collapsed too, the dark smoke puddling on the ground and flowing back into Albert like black mercury.

  ‘Bertie equals monsters squared,’ the Doctor murmured.

  Mileva was kneeling next to her fiancé, cradling his head and stroking his hair. ‘My darling, what has happened to you? How can I save you?’

  The Doctor gazed at her for a moment. ‘You’re an incredible woman, Mileva. How much are you willing to risk to help save him?’

  Mileva looked up at her, eyes blazing. ‘Everything.’

  The Doctor nodded. ‘Then, in the few minutes we have before he wakes up, we need to talk. Yaz, come and plonk yourself down. It’s Plan Time.’

  There was a surprising amount of cloth in the cathedral once they started to collect it. Surplices, cassocks, chasubles, veils, curtains, mufflers for the bell clappers …

  Once the police understood what Graham and Ryan were suggesting, they took charge of the situation, marshalling volunteers into a chain, passing out extra materials and carrying out their own searches for more food. More and more candles were lit, providing small globes of light around the cavernous hall. Outside, a slice of moon was rising in the clear sky, casting a pale gleam through the tall windows in the choir vault at the east end.

  Ryan cursed as he fell down the last few steps of the bell tower, dropping his bundle and spilling hot candle wax onto his hands. ‘I hate stairs.’

  ‘Look what I found!’ Graham brandished a wooden box triumphantly. ‘Marzipan!’ He passed it to a man at the end of a pew, who took it gratefully.

  ‘I have not eaten since yesterday,’ he said. ‘Thank you.’ He took one sweet out of the box and gave it to his wife. Then he took one for himself and passed the box along to the next family.

  ‘That’ll only be enough for a few people,’ Ryan said.

  ‘But those few people will feel better for it,’ Graham pointed out. ‘Besides, haven’t you heard the story about the loaves and the fishes?’

  ‘We ain’t got any of those,’ Ryan said.

  ‘No …’ Graham watched the box as it was passed along from person to person, each taking only one sweet, ‘but you watch …’

  People started to open their bags, to pull out wafers, dried meat, bread rolls. The marzipan was soon gone, but the box kept going. Nearly everyone who took something out of it put something back in. Soon the box was fuller than it had been to start with.

  ‘People take,’ Graham said quietly, ‘but they give back more. That’s what the loaves and fishes were all about.’

  ‘Graham?’ Marthe had made her way over to them. Her face was strained. ‘Johanna … she’s getting worse. We’ve been giving her sips of water, but now … Will you come?’

  They followed her back to Friedrich, who still held the unconscious child across his knees. He looked up at them, fear in his eyes. ‘She sounds like she can’t catch her breath. Listen.’

  Graham bent over, and could hear the breath stuttering in Johanna’s throat. Her eyes no longer flickered under their lids, and when he felt for her pulse, it was weak and trembling.

  ‘Is she … dying?’ asked Marthe, her own voice catching on the last word.

  Graham said helplessly, ‘I don’t know.’ He placed his hand over the other man’s. ‘Don’t give up hope. Our friends out there are trying to help, I promise.’

  ‘You are helping,’ said Marthe quietly. She took Graham’s other hand. ‘If you say there is still hope, then that gives us strength. We will try to believe.’

  ‘So let me get this straight,’ Yaz said, rubbing her head. ‘You’re going to try to lure all the starfish into one place, and trap them?’