Saskia kept her neck stiff. There was barely enough space between the dirt walls to look left or right. So she kept her eyes focussed on Hartlepool’s back as she followed him through the tunnels.

She was glad that Hartlepool couldn’t turn around. She didn’t want to look at his face. Even though he had only killed the Guard to help them escape from jail, Saskia felt uneasy. The word ‘murderer’ echoed through her brain. She tried to concentrate on the musty smell but she couldn’t stop thinking about the cracking sound when the Guards’ neck broke.

She tried to count her steps, remember the words to a popular song, anything to stop  thinking about it. But she soon realised that trying to distract herself left room for the other thoughts. Murderer. It wasn’t worse than what she had done. What brought her here in the first place. She had committed murder too, in a way. Yet she had killed someone who wanted to die. Herself.

‘Where are we going? This is crazy,’ said James.

‘You must be quiet,’ Hartlepool replied.

‘I’m tired of shutting up and doing what you say. Even if we do get out, how are we going to find Queen Rat’s kids?’ James shouted.

‘It’s obvious,’ Hartlepool stopped abruptly causing Saskia to bump into him. ‘Heterochromia. Everyone knows that one of their eyes is green and the other is blue.’

‘What?’ Saskia instinctively grabbed his shoulder.

‘Each eye is a different colour,’ Hartlepool sighed, exasperated at having to explain each tiny detail.

‘So, we get back to the surface and go round staring into strangers’ eyes? Right, that’s going to work. Good plan…’ Jack muttered.

‘I can get you above the water. Once you’re out of the River it’s up to you to work out how to save the humans. They are your people.’

Hartlepool urged them on. The path started rising upwards as a gentle slope. However it became steeper and steeper until then Saskia felt out of breath. Eventually they were almost climbing upwards through the alleys. Soon they had to stop. There was a vertical wall with a small grate in it – a dead end. A confused Saskia tried to peer through the thin metal bars of the grate but Hartlepool pushed her back. He simply tapped on each of the four corners and the iron grille fell away.

‘We’re not…’ Saskia started.

‘You have to,’ Hartlepool said gently. ‘You’re both small. You can crawl through.’

‘You first,’ James demanded.

‘I can’t,’ Hartlepool said slowly. ‘I don’t know what waits on the other side but I can’t accompany you.’

‘You’re leaving me,’ Saskia said, putting her hand to the scar across her neck.

‘I can’t go above the water. This is my home. I’ll die on the surface.’

‘But…’

‘But you must hurry. The Queen will be searching for us. Don’t worry about me. You must go now.’

‘What will Queen Rat do to you? Will I see you again?’

‘No. Probably not,’ Hartlepool’s wrinkles slipped into a wry smile. ‘But I don’t regret saving you.’

He pushed away Saskia’s braids and kissed her forehead. ‘So go! Save your city from the flood.’

Saskia went first. She crouched low to enter the hole in the wall and crawled on her hands and knees. She kept going until there was a bright light and she had to pause to shut her eyes. After her moment to recover she started moving again, partially blinded, when she felt the floor disappear beneath her. Before she knew what was happening she had tumbled into a large room.

Slowly regaining her vision, Saskia blinked. She tried to stand up but her feet recoiled against the cold stone floor. Gaining her balance, she noticed the rows of tall pillars holding up the ceiling. They went on for ages, like soldiers standing to attention in rigid formation. And in the corner, at the back of the room, was a small staircase.

‘Are you OK?’ Saskia asked James as he fell into the room after her.

‘I guess…’ she said pointing at the stairs.

They had to walk carefully up the worn stone ledges, brushing bits of rock that had crumbled away off their legs. And with every step, Saskia began to feel strange. She was hot. And her eyes stung. And her hair was light. She hadn’t realised it had been weighing her down.

‘Can you?’ she started.

‘Yeah.’

‘Weird.’

‘Look!’ James pointed to a small glass window at the top of the stairs.

It wasn’t particularly fancy or peculiar. It was just a bit old fashioned, with a black hashtag across the glass and a heavy latch. Then Saskia realised James was pointing at the sunlight. As they rushed upwards a beam of yellow warmth fell across them. They pressed their weight against the window and forced it open to stick their faces out. Fresh air. The wind tickled them and they giggled at the crisp winter breeze on their skin. The waft of air whipped up water from the river below, which flicked onto the underside of their chins.

‘We’re out! We’re out! James exclaimed.

‘Hold on,’ Saskia said, trying to calm him down. ‘We’re above the river but below street level.’

Opposite them, over the wide expanse of water, was a brick wall below a bustling bank.

‘Look left… Isn’t that the London eye? I can just about see a pod,’ Saskia said before her words were eclipsed by a loud dong, which reverberated around the room.

Saskia dragged James away from the window. They walked away, into a stone corridor with wrought iron fixtures on the walls.

‘I think I know where we are,’ Saskia whispered.

They kept walking through the corridor, past old wooden barrels and stacks of ancient crates, until they came to a brick wall.

‘This is just a maze! What do..’ James said, leaning back against the bricks, which creaked open.

‘I feel like Guy Fawkes,’ Saskia said grinning, as they went through the secret door and emerged out of an old fireplace in Westminster Hall.

 The MPs and tourists milling about didn’t even turn to look at the two teenagers creeping out of the wall. Too busy on important business or listening to guides, they went about their lives.

‘C’mon,’ Saskia said to James as they ran to join a large tour group. They shuffled out of the House of Commons, past the cumbersome security checks. But, when they were finally free on the street, Saskia and James didn’t know what to do. With no clear direction to go in, they stood back and looked at the old abbey.

‘So… Are we still saving London from a giant flood or was that just a joint hallucination?’ James asked.

‘It feels so bizarre to be back to normal. But that all just happened. We can’t pretend it didn’t. We need to do something.’

‘Don’t suppose we can see if the Prime Minister’s around. P’raps he can help?’

‘Don’t be stupid,’ Saskia said. ‘We need to find Queen Rat’s children.’

‘But how are we going to do that? One green eye and one blue. That’s not much to go on.’

Saskia put her hands to her head and leaned back to look at the sky. Taking a deep breath, she counted to ten before turning her gaze on James.

‘I know,’ she said quietly. ‘I know someone with different coloured eyes. I know where to find them too.’

‘Blimey, why didn’t you say before?’

‘Doesn’t matter. Follow me. I know where to go.’

#

They crept through an old hospital. Their footsteps hardly made a sound on the easy-clean lino floor. Despite the walls being painted baby blue and sunshine yellow, the place was still depressing due to the forced attempt at cheerfulness.

James wanted to say something but didn’t know how to break the silence. There wasn’t a reason why they weren’t talking. There was no one around to catch them, the place was deserted, but James didn’t know what questions to ask and Saskia didn’t want to explain.

‘Nightingale Ward,’ James read aloud. ‘Mental health.’

Saskia nodded slightly, her hands trembled as she went to push open the door.

‘Wait,’ James put his hand on hers. ‘Before we go any further, you’ve got to explain.’

‘What’s to explain? There’s a magic world under the River Thames and they’re going to flood the city to take control of London and the only way we can stop it is to hope we can persuade the most frightening person I’ve ever met to..’

‘No, explain why. Why are you part of this in the first place?’

‘Why were you there?’

‘I drowned. Or, I think I drowned. I got drunk with some older kids. We were hanging about by southbank. I missed the last bus and decided to walk but I stumbled into the river on my way home. I was being stupid and it’s all my fault. But what about you?’

‘I jumped.’

‘Why?’

‘Because…’

‘There’s never a reason why,’ a soft female voice floated through the crack in the door. ‘If there was a problem, there’d be a solution. But there’s not one why for people like us. There’s millions. You miss the bus. You accidentally bump into someone. The shop you went out of the way to visit didn’t have the brand of baked beans you like in stock. Everything’s a why if you want it to be.’

Saskia and James stared at the girl’s face poking through the crack in the door. They were mesmerized by her beautiful pale skin and raven dark hair. Enraptured by her perfect red lips. And transfixed by an eye of dull algae-green and the other, a muddy-water blue.