‘And many worlds is one price? What does it mean?’ She bit off half the casing from her second brazil with small white teeth, exposing the nut.

‘It applies whenever any choice is made. You can think of those choices as you choosing to stay in or go out, but it really means whenever anything that has multiple possible results happens. And it says that each time a choice is made the universe splits, and there is a universe in which each possible outcome happens. And those universes go on and do their own sweet thing forever after without ever interacting again.’ I sketched a tree on the notepad beside me, explaining that the trunk represented our timeline and that at each fork of the branches lay a decision, splitting the universe’s timeline into multiple new timelines. At the tips of the smallest twigs lay all the possible outcomes, a multitude of timelines waiting to be split yet again by new choices. ‘Basically, we’re all infinite.’

‘Wow.’ She sucked her fingers.

‘Yeah . . .’ I looked away from her red lips and tried to regain my train of thought. ‘So, there is a universe where Nick Hayes has rolled a one every single time he ever threw a die. And a trillion others where he hasn’t. In that one universe he’s probably famous and gets on TV shows. And the thing is, it’s just regular chance. Each time he rolls a six-sided die again, he has exactly the same probability of getting a one as everyone else, and in five of the six branching universes, the TV hosts blink and Nick says, “But . . . it always works . . . I don’t understand . . .” But in one of the six, Nick chalks up another victory and the world thinks it’s a trick or magic.’

‘That’s legitimately mad.’ Mia nodded. ‘So . . . in one universe, one of my premium bonds wins the hundred-thousand-pound prize tomorrow?’

‘Yup. In fact, there will be a universe where all of your premium bonds win a prize tomorrow . . . and then you’re killed by a meteorite.’

I didn’t even notice Mother come in to deliver the drinks. We talked for an hour or more, physics mostly. It didn’t matter to me that Mia had probably come out of pity, and that if I weren’t dying of leukaemia, she wouldn’t have come within a mile of me without John or Elton on her arm. I just enjoyed being with her.

‘I gotta go.’ Mia glanced at her watch and brushed her hair out of her eyes. She looked at the bedroom door that Mother had left decidedly ajar. ‘I, uh, got you something else.’ She kept her voice low and placed a small black rectangle between us, wrapped in cling film. At first, I thought it was a strange bar of chocolate. ‘It’s supposed to help with the pain and feeling sick.’ She bit her lip. ‘I read up on it.’

I wasn’t a hundred per cent sure, but I thought it was probably cannabis resin. A lot of it. ‘I . . . Thanks. But I don’t—’

‘I know you don’t smoke.’ She grinned. ‘You faked it better than John, though!’ The grin broadened. ‘But you can eat it. Not more than this.’ She showed half the nail of her little finger. ‘Just thought it might help.’

I looked down at the rectangle. Then covered it with my hand as she withdrew hers. ‘Thanks.’

‘No problem.’ She got up to go, stealing one last chocolate. ‘Saturday.’ She paused at the door. ‘Or we all come here.’

CHAPTER 6

I made it to Simon’s house on Saturday. Mother gave me a lift, which was nice of her because I don’t think I could have walked it. My third round of chemo was really starting to bite. The resin helped, though it made Mother think I was more ill than I was. It also made concentrating on quantum mechanics textbooks difficult, so I took the minimum required to lift me far enough out of the pit to function, without going too high to care.

The night had been sleepless, adrift on a black sea of self-pity. And why not? I stared at the dark, one thought churning over the next. I’d always had the sense of a whole life ahead of me, an endless series of sunrises and sunsets. A decade seemed like forever, and it would take two of them just to reach the age my mother was right now. Cancer had closed that down. Like the big C, curling in on itself, my view of the future had narrowed to tunnel vision, aimed squarely at the next week, next month . . . would I have a next year? I was carrying not only the burden of my sickness but the pressure of making something worthwhile of each day now that my towering stack of them had fallen into ruin and left me clutching at each hour as it slipped between my fingers.

I sat yawning in the back of the car, like a kid, staring at Demus’s note. It had two words on it and ten numbers. ‘BATTER UP.’ Written in crudely drawn capitals as if a child had done it. I’d memorised the numbers: 4, 17, 17, 6 . . . it went on. I tried to fix them in my mind. Simon could lock a sequence of numbers into his head at glance. I’d always struggled with memory. Phone numbers leaked out of me. So it was probably good I hadn’t many friends. Understanding was a different matter. I could get an idea quick enough, but a list of numbers . . . even without the dope I’d be struggling.

Simon’s mum greeted me at the door rather than Simon. She waved to Mother, still parked across the road, signalling in some universal mothering code that I was in good hands.

‘The hat suits you.’ She gave me an unexpected hug and aimed me upstairs. ‘They’re all here already.’

I winced my way up the stairs. On the oncology ward, I was still synchronised with talkaholic Eva. She continued vomiting like a puke-fountain, but in between she said she felt fine, and her dull brown hair was still clinging uninspiringly to her skull. Of all of them, I seemed to be winning the race to the bottom. The nurses tutted to themselves, the doctors puzzled over blood counts and clotting factors. The white walls and starched uniforms were failing me. Their poison was hurting me more than it was hurting the rogue cells filling my veins.

‘Holy cornflakes! It’s hat-man!’ John raised his coke can in my direction. The table was decked out: dice ready, maps sorted, figures positioned.

‘How you doing, Nick?’ Elton got up as if I were an elderly relative who might need helping to my chair.

‘Of all the worlds, in all the universes, he walks into mine.’ Mia wrapped the Casablanca quote around Everett’s many-world interpretation and gained yet another level in my esteem.

‘You’re late.’ Simon didn’t look up from his character sheet. I’d known him pretty much all my life. He was the way he was. So much of what he felt couldn’t ever crystallise into something small enough for words or action. Instead it raced around in his skull, winding him tighter and tighter. I wouldn’t ever know more than a fraction of what was going on with him, but I knew enough that we could be friends.

‘Woah.’ As I sat down, I saw Mia’s black eye for the first time. ‘What happened?’

‘You should see the other guy.’ She made an unconvincing smile.

‘But what—’

‘It’s not important.’ Mia looked pointedly at Elton, who frowned but took his cue and began the game.

‘The fortress backs against a granite ridge. It’s half-ruined now, but you can see that once it was magnificent. It covers acres. The morning sun’s just starting to catch on the towers. Down below it’s all shadows . . .’

The game went on its way, Elton’s skill drawing us in and wrapping us in his imagination. The rest of the world faded into the background, taking most of my discomfort with it. Only the square of paper in my pocket kept me anchored to something outside the fortress we had to search.

Elton had us creeping through darkened halls hung with dead ivy, forcing ancient doors, descending into the subterranean levels below the vast fortifications. Hours slipped by. It was almost time to go before I knew it.

‘The chamber’s huge,’ Elton said. ‘You could drive a double decker bus through it, and there’s shafts of light here and there from openings in the ceiling, leading up to the outside.’

‘So, we’re blind then,’ Mia said.

John frowned. ‘He just told us there’s light.’

‘Yeah, but like spotlights: patches of brightness that take away your night sight and hide what’s in the shadows. And Simon’s lantern isn’t going to touch a place this big . . .’

‘Fineous,’ Simon muttered. He always wanted to be addressed by his character name in the game.

‘Sorry.’ Mia didn’t look sorry. ‘Alright, Fineous, how about you shoot an arrow or two out there and see what you stir up?’

Simon shrugged. ‘I put my lantern to one side, get out my short bow and loose an arrow toward the back of the hall.’

‘There’s a cry of pain,’ Elton said.

‘Shit.’ I moved Nicodemus behind the armoured bulk of John’s warrior.

‘Why shit?’ he asked.

‘He didn’t roll,’ I said. ‘If Elton didn’t roll to see if the arrow hit anyone . . .’

‘That means the place is full of them!’ Mia said.

‘They come boiling out of the back of the hall.’ Elton began gleefully advancing orc figures. ‘Dozens of them. Big Uruk-Hai in chainmail, ogres, too.’

John moved his warrior behind my mage. ‘Batter up! Time for a fireball!’