Read Online The Impossible Clue by Sarah Rubin - Free Book Online

just showing her how the invisibility cube works. It isn’t top secret. You can see videos on YouTube.’
    Graham got four pairs of safety glasses off the shelf and handed us each a pair.
    â€˜I need something small. This only works on a very small scale.’ He patted his pockets like an old man looking for his keys. ‘Ah,’ he smiled, then took the ruined pen lid off the biro in his pocket and put it inside the box. ‘Are you ready?’
    I put on the glasses and nodded.
    Graham flipped the switch. The machine started to hum and the cap was gone. Instantly, like it had disappeared off the face of the Earth.
    â€˜Wow.’ It was all I could say. It was still only invisibility on a small scale, but it was a lot bigger than I thought was possible. Maybe Sammy hadn’t been exaggerating about how smart Dr Learner was after all.
    â€˜Touch it.’ Davidson nudged my shoulder.
    I reached out my finger towards where I last saw the lid. I could feel it. It was still right there inside the cube. But I couldn’t see it. I couldn’t see the tip of my finger either.
    We see things because light bounces off them and back into our eyeballs, which is why you can’t see in the dark. No light, no sight. Normally, light moves in a straight line, but Dr Learner’s machine must have been bending the light around the pen lid. It was making it invisible. It was so cool I didn’t even care that I was touching something that had been in Graham Davidson’s mouth.
    â€˜Is this related to the breakthrough Dr Learner had?’ I asked. ‘Was he trying to make this work on a larger scale?’
    â€˜What?’ Graham turned off the machine and the black lid popped back into view.
    â€˜Mr Delgado said Dr Learner had a breakthrough. He had a press conference yesterday to unveil the results. Well, he would have if Dr Learner hadn’t gone missing.’
    â€˜A breakthrough?’ Graham looked confused. ‘Not that I knew about, not that Dr Learner would share any of his important research with me. Oh, no. I don’t know why he wanted a lab assistant in the first place, unless it was to have someone to get him coffee. He never had any appreciation of my skills. He never even let me babysit experiments for him. He’d be here all hours of the night because he couldn’t bear to leave an experiment unfinished and he refused to let me help. And that was before he got super paranoid.’
    â€˜Wait.’ I held up a hand to stop Graham’s rant. ‘Did something specific happen to spook Dr Learner?’
    â€˜It wasn’t anything I did, if that’s what you’re implying.’ Graham searched me for an accusation. ‘But maybe you’re right. He did get a lot worse about six months ago. He even started taking his notes home in a locked briefcase every night.’ Graham trailed off as if he’d thought of something important.
    â€˜What is it?’ I asked.
    Graham shook himself. ‘What? Oh, nothing. I just remembered I have to do something. Are you just about done here?’
    I wanted to ask what Graham had remembered. I was pretty sure it had something to do with that briefcase, andI wanted to know what it was. Maybe Dr Learner had figured out how to make the invisibility cube work for larger objects. But Andrew butted in first.
    â€˜Yes, I think we’re just about finished here.’ He looked at his watch. ‘I need to go collect Mr Delgado from the unive— Mr Jones!’ Andrew spoke sharply, and my dad quickly put down a small soldering iron.
    Andrew took a calming breath and herded us all out of the room. Graham Davidson left too, locking the door behind him. I wondered if he was allowed to go into Dr Learner’s lab without supervision. If it was me, I’d spend all day playing with that invisibility cube. But I guess the security camera meant he couldn’t sneak in, even if he did have the key.
    I looked