I was paying no attention to the real time – the time on my watch. My dad’s words had me spellbound and I read on, transfixed.

It doesn’t hurt, Al. You don’t feel anything, really, though your vision blurs a little.

In fact, I wasn’t even certain that it had happened at all, until I stepped out of the tub and checked the date on my phone: eight days had passed.

I wanted to see more – I wanted more proof. So I came out of the cellar and headed into the house.

I really had no idea what to expect, but in my most vivid imaginings I did not anticipate that I had died.

It was early evening when I came from the garage into the kitchen. I heard voices in the living room – your mum, and a man’s voice I didn’t recognise. Something made me hold back on my urge to rush through and tell your mum, “Hi – I’m from the past!”

I was also very scared of bumping into myself. My future self. I wasn’t aware at that stage that such a thing was not possible – but I’ll get to that.

The Whitley Bay Advertiser was on the kitchen table, and I wanted to double-check the date. That’s when I saw it. In that moment, everything changed.

The headline on the open page: “Local Man’s Tragic Sudden Death: ‘Walking time bomb’ says Coroner”.

The newspaper was open at the page where there was a picture of my dad, one I hadn’t seen before. He looked nice. He had a tie on.

That hit me pretty hard, I can tell you, Al. Not many people get to read their own death notices.

I was in a bit of a daze when I wandered through to where the voices were.

Your mum was talking to Dennis Harrison, the funeral director. I backed out of the room, and I don’t think she saw me.

“No, Dad: she did,” I said out loud to no one, and the sound of my voice made me jump.

I kind of panicked. I grabbed the newspaper from the kitchen table, hurried back to the cellar, and reprogrammed the laptop to return me to where – and when – I had begun – that is, eight days ago.

And then I sat, in the seat you’re in now, in a stunned stupor. I wanted to know more about my death, and – obviously – if it was preventable.

You’ll remember that occasionally I suffered excruciating headaches? I just thought they were normal: everyone had headaches now and then, right? I had no way of comparing mine with anyone else’s, no way of knowing that mine were a symptom of something much worse. I would take painkillers, and I once consulted my doctor after a particularly bad one that had lasted a couple of days, and left me weak and exhausted. But he just prescribed some extra-strength painkillers, which I put in the bathroom cabinet because the pain had gone by then.

That piece of metal in my brain has been moving since it first got there – on August 1st, 1984, the day I came off The Lean Mean Green Machine and smashed my face up. Do you remember the story I told about the spike that went up my nose, which someone pulled out? A small piece was left in, and that’s the piece that will kill me in few days’ time.

This is where you come in, Al.

I need you to use my device – follow the instructions incredibly carefully – and prevent me from having that accident.

Remove the brick from the path – the one that caused the accident.

Remove the mangled-up metal trolley from the side of the path.

And Al – come back safely. Remember to keep the laptop with you at all times.

Whatever is with you in the zinc tub will travel with you to the spacetime dimension that is your destination.

Without it you are, to put it bluntly, stuffed.

I’ll bet you have some questions. Let me try to anticipate them.

Why me, why now? As I discovered when I tried to travel an hour into the future, you cannot be in the same place as yourself. This we will call Dad’s Law of Doppelgangers. A doppelganger is a double of yourself. They have existed in stories forever, but for a reason I have yet to discover – but which we might, when we continue my research – the laws of the universe prevent you from encountering your own self. So you cannot go forward in time, or back, to meet yourself.

For this reason, neither of the two other people I might trust with this could do it – your Grandpa Byron or your mum.

Your mum is a wonderful person, Al – but I don’t think she has the courage to help you to do this. A mother’s instincts are to protect her child. She would stop you. I can’t blame her for this, and nor should you. Just don’t tell her, OK?

And your grandpa? What can I say, except that – love him as I do – he doesn’t trust my work in this area. I tried to talk to him about it once, and he shut me right down. “These are not suitable subjects for study, Pye,” he told me. “You are venturing beyond human limits.”

Except I don’t think there are human limits, Al. Who determines that?

“Great question, Dad,” I’m thinking. “Only not the one that’s in my head right now.”

And that is: why involve me in all this? Why not just go to the future and stay there? You could, I don’t know, reappear at your own funeral as your long-lost identical twin or something? I’m thinking this as I read on and it’s like Dad can read my mind.

Do you have to do this? Well … I’m hoping not. As I write this, I’m hoping that my first or second plan will work. If it doesn’t, you will be reading this.

So what’s Plan A?

Tomorrow, I will present myself at the doctor’s, complaining of severe headaches, demanding tests, x-rays, scans, anything I can to stay in hospital so that if – I should say when – the haemorrhage happens, I will be better placed to survive it. If I don’t survive it, well – you will get this letter on your twelfth birthday. Risky? You bet.

There is a Plan B as well. (As the great mathematician James Yorke once said: “The most successful people are those who are good at Plan B.”)

Plan B is to travel into the future, to a time after I have died and … carry on living. There is (as I discovered) clearly no physical law that prevents me being in the same spacetime dimension as my own corpse.

I can only presume that this is to do with notions of consciousness or what your Grandpa would call “eternal spirit” and is among the reasons that I am so desperate to continue my research.

But exactly how this will work I have no idea. I need a little time to consider this. Do I just reappear a few days after my funeral …

I find myself nodding as I read this. “As your identical twin!” I say. (I’ve probably seen this in a movie or read it somewhere. It’s quite dramatic, especially if he grows a moustache or something.)

…or do I try to time my return to coincide with my death, without being seen, and somehow dispose of my corpse secretly, then carry on as if I had not died?

My mouth is hanging open at this point.

I know: it sounds unlikely, or impossible, or ridiculous … or all three. Think about it, Al – can you really see me secretly getting rid of my own corpse?

No, nor can I.

And all the while I will still have this death sentence hanging over me, this piece of metal in my brain, which I will have to deal with – whatever happens.

And so – to you, Al. My Plan C.

There are dangers, for sure. But I trust you, Al. You are now twelve, an age when I believe you will be able to carry out this amazing task, if it is required.

And when it is done, you and I will carry on this work, which will change the world in ways we cannot even imagine, answering questions that have been asked since the beginning of mankind’s journey on Earth.

I really don’t want you to do this, Al. But if you are reading this, then I promise you there is no other way.