You know when you forget your coat? Or leave your phone at your mate’s house? And your mum says, ‘Where’s your coat?’ And you say, ‘Oh! Sorry – I forgot it.’ And you promise to get it back the next day.

It’s not the same if you leave your hand behind.

If you lose your flesh-job hand, people come running round to take you to hospital, send you cards, say nice things and – in the end – fix you up with a brand-new state-of-the-art replacement hand.

If you lose your brand-new state-of-the-art replacement hand, they’re not going to be nice about it. Leave your state-of-the-art hand somewhere, and difficult questions will be asked.

And the answer to one of those questions will have to include, ‘I swerved school and went to the airport.’ Which is not a sentence you ever want to have to say to your mum.

There was no way I could leave the airport without my hand.

Luckily the Osprey Grip MM has its own little app that synchs with your phone. It’s called HandShake. It looks like a hand with its fingers spread out. The fingers disappear one by one as the hand’s battery fades. It’s also got a ‘Where’s My Hand?’ button, which helps you locate your hand.

Turns out, my hand was still on five fingers’ worth of battery. And it was still in the airport. And I probably would have found it if one of those electric luggage buggies hadn’t come between me and the door. Its klaxon was beeping. It kept saying, ‘Excuse me, please. Unstable load. Thank you.’

I stepped out of its way and saw what the unstable load was.

It was the robot.

It lay across the back of the trolley. It wasn’t dead because it had never been alive, but it really did look dead. Its joints chimed like church bells when the trolley stopped to wait for the airport doors to open. I followed the trolley down the ramp. It crossed the short stay car park, heading for the multi-storey.

When the trolley stopped by the service lift, the robot’s head turned towards me. The lift doors opened. The trolley wheeled itself inside, still saying, ‘Unstable load. Thank you.’

As the lift doors began to close, the robot’s eyes flickered. It was staring at my hand.

No, not at my hand. At its own huge metal hand. Was it asking for its hand back?

The lift doors closed.

The robot vanished from sight.

I could have turned round then and walked away.

But I didn’t.

I had to give him his hand back.

I charged up the stairs.

I chased the lift up to the roof.

If I hadn’t done that, none of this would have happened.

The trolley had already trundled out of the lift by the time I got to the rooftop. It had parked itself in the middle of the wide, empty space. It was proper windy up there, and noisy – like someone was beating the air with a massive whisk. I didn’t notice what was causing that at first. All I noticed was the robot. It wasn’t lying on the trolley any more. It was standing up on one leg. On tip-toe, like an armoured ballet dancer.

‘Hey!’ I shouted, over the noise.

Then I saw the helicopter, hovering right over his head. That’s where the noise was coming from. It was small and white with POLICE painted on its side in black letters.

The robot’s toes drifted off the floor. He was floating up into the air, swinging like a pendulum, every swing taking him a little bit higher.

A long cable dangled from the helicopter’s hatch, like a fishing line.

Then I realized. The robot was attached to the end of the cable.

‘I brought your hand back!’ I shouted over the noise.

THANK YOU.

It really was a polite robot. Even when it was dangling from a long metal cable, suspended from the belly of a helicopter, it remembered to say thank you. As it twisted in the air above me, it held its one hand out towards me.

‘Oh right! Sorry! Nearly forgot!’

It wasn’t easy, fixing the hand back on the dangling robot’s wrist, especially as I only had one hand myself. The robot helped me by twisting its wrist on to the thread inside the hand. He held out his hand for me to shake.

I made a grab for it with my right hand, totally forgetting I didn’t actually have a right hand. Just the ghost of a right hand. It passed through the air like light through a window.

Then something grabbed me by the wrist and hoisted me into the air. The robot. He lifted me level with his face and stared into my eyes.

‘Hi,’ I said, under his blazing blue gaze.

I was about to say, ‘I think I’d like to get down now,’ when I realized I was no longer dangling three metres above the roof of the multi-storey. The helicopter had moved over the edge. I was now suspended about thirty metres above the tarmac. The runways spread out beneath me. Planes were queuing up for take-off. Lego-sized people were hurrying around. I tried not to look.

‘We’re going to fall,’ I said. ‘We’re going to plunge to our doom.’

The robot put his hand under my arm and hoisted me up to his chest.

MY NAME IS ERIC. HOW DO YOU DO? WHO ARE YOU?

‘Hi, Eric,’ I said. ‘I’m Alfie. PLEASE. Do. Not. Let. Go . . .’

I AM YOUR OBEDIENT SERVANT.

We swung out high over the Skyways estate. Hey. Guess what. The whole estate – the roads and avenues – was shaped like one massive aeroplane spread out on the ground. That’s what it looks like to people arriving at the airport – a gigantic aeroplane.

‘Where are we going?’ I wondered out loud.

I CAN ANSWER ANY QUESTION.

‘So, where are we going?’

I’M SORRY, I CAN’T ANSWER THAT QUESTION.