"What the?" Juan exclaimed. Neither of us had seen a summary execution before. The presence of Enforcers deterred most forms of crime.

Even though the man must have been a serious offender, human instinct is hard to overcome. That's my only explanation for what I did. Juan looked away - that's what you're advised to do if you find yourself in the vicinity of a summary. Most people will never see one in their entire lifetime. Summary executions were quick and bloodless, using pistols that did something terminal to the nervous system. The next I knew, I had launched myself at the Enforcer as though I were in martial arts class and I'd kicked his faceplate. He dropped the pistol and went down with a dent in his faceplate. He wasn't hurt though, just thrown off balance. Machines don't get hurt that easily. Next I knew, he was getting up and another Enforcer was coming into the yard off the street that ran behind our offices.

Since I've got time, let me explain about Enforcers. They're humanoid machines that take the place of a police force and army and maintain law and order in society. They are look like humans, wear human clothes (the police types wear army khaki) but they have no features. Instead of a face, they have a grey featureless ovoid head. That's right - no eyes, no nose, no lips; not even hair. This is psychological - if something doesn't have features or facial expressions, you're not inclined to argue with it. Being machines, they are thoroughly expendable and replaceable. Like most people, I've seen the documentaries about how they are built. Underneath the grey faceplate - which is soft rather than solid - is a mess of sensors and electronics.

The Enforcer I'd kicked in the faceplate now had a dent across the place where a human would have a nose. I realised I'd committed a criminal act and was in deep trouble - you can't reason with an Enforcer that you'd acted instinctively. The thought of mental correction was not attractive so I did the next instinctive thing and ran towards the street, planning to dodge the other Enforcer. When I tripped, I did something else instinctive. Instead of reaching out my hands to break my fall, I reached out my mind. It's hard to explain. Imagine your mind projects out of your forehead like an arm and you can use it to push against things. That's what I did. My mind instinctively pushed against the ground and the ground pushed back. The next thing, I found myself floating 6 feet in the air and still moving forward. I rose over the head of the second Enforcer and shot forwards over the heads of surprised people in the street. Before I crashed into the wall of the commercial bank, I pushed against that with my mind and changed course. It was like swimming in air.

Imagine you are standing facing a wall. You put the palms of your hands on the wall and you can push hard enough that you have to take a step back. At first you can push pretty hard, but once your arms are braced straight you run out of force. You can extend your fingers to push yourself another few inches away, but once you lose contact with the wall, you lose push. That was what it was like. I could easily get to 10 feet above the ground. By giving little pushes I could get to 12 feet but not stay there - that was fingertip length for my mind. Trying to go higher was like bouncing a ball, I always came back to that 10 foot maximum height. Changing course was a case of pushing against something vertical like a building - for every action there is a reaction. Going forwards was easy - it just happened and I kept going in a straight line unless I wanted to slow down. It was all Newton's Laws of Motion. The speed was infuriating though; I could only go as fast as I could normally run on foot.

The people, and several Enforcers, were looking up at me. By now the Enforcers had radioed my description to each other so I had no choice but to keep on going until I either ran out of push or got shot down or pulled down. Somehow I made it through the shopping streets and to the edge of the commercial development into the undeveloped area. Luckily it was a commercial complex with no residential districts and once I was out of the commercial part, I was into open countryside, roads and railways. I kept on going over countryside, coming down a few times during the day. For one thing I knew I was being tracked. It hurt like hell, but I ended up cutting the citizen transponder out of my arm using the penknife on my key-ring. For the next three days, I alternated between walking and flying, slept on roofs(!) and lived on fast food until my cash ran out. I didn't dare use a bank card as the network would immediately report my position.

I didn't see another Enforcer until I reached a cliff near some town. It wasn't a sea cliff, but a ridge where the land had split across and part of it had risen up. It was all unfamiliar territory. At the top of the cliff was a disused machine building - a huge Victorian brick building which had once housed factory machines or pumps or something. It is all tumbledown now, probably a victim of the earthquake that happened when the land split. A hiker was reading a map, probably looking for a way down. By then I was also walking and wondered if I should ask for a look at the map as I wasn't sure where I was - things look a lot different when you're flying and it's easy to lose your bearings. That was when I saw an Enforcer and I could see from his purposeful approach that he had recognised me. I took off - literally - and went over the head of the startled hiker who yelled out a warning. It was just a bounce and I came back down running straight towards the edge of the cliff and it was a lot deeper than 10 feet. I decided to take my chances and jumped into empty air.

The ground approached at dizzying speed and it looked like I'd be smashed on the harp rocks at the foot of the cliff, but once I was 20 feet away I began to feel the ground pushing back. I pushed frantically with my mind. At 12 feet I slowed and then I felt it push back solidly against my mind. My landing was bone-jarring rather than deadly and I set off on foot. The only place I could go was towards the city at the foot of the land-cliff and hope that I could dodge Enforcers for a bit longer. I'd gotten rid of the citizen transponder and I was bedraggled and had lost weight, so perhaps I'd be harder to recognise among the down-and-outs you find in any big city. Breaking my fall had exhausted my mental push, so I had to go the rest of the way on foot.

Before I even got to the first buildings (an out-of-town shopping area) I had a meeting committee. One was the dented Enforcer. The rest were just faceless Enforcers. I was too tired to lift off the ground and two Enforcers bundled me into a police van. I was so exhausted and there were no windows in the van so I actually fell asleep. Later, I learnt they'd used a sedative gas; Enforcers, of course, don't breathe. I was tired and confused and I don't remember much about being booked in at the Enforcement centre or being put in this room. There was a human - at least I'd thought he was human - who talked to me about flying and over the next several days I learnt a lot about recent history and the Enforcers. I wasn't going to get out of that place so it didn't matter to them if I learnt these things.

The man (no-one seemed to have names there, but he was the only one with a white coat and I thought he was probably a doctor or, more likely, psych doctor) told me that Enforcers had been built to replace human police and armies. I'd already known that. Having imposed law and order, the Enforcers didn't stop there. At that point, the man reached up and scratched his hairline. He peeled his face downwards and underneath the thick, rubbery skin was the same mess of electronics that you find under an Enforcer's faceplate. To cut a long story short, over the years humans had delegated more and more tasks to humanoid machines. The machines built more and better machines. They built ones that looked and acted like humans. Gradually, the balance of power shifted so that machines ran things. Humans, with their naturally dwindling birth-rate, were too busy to notice that they were being replaced. Nature wasn't too busy though, and a few humans were showing up with odd powers and an instinctive resentment of Enforcers. To maintain the status quo, we had to be removed from the equation.

There were a few loose ends I wanted tidied up. How had the Enforcers found me? The white-coat told me that humans had two tracking devices. The citizen transponder that supposedly protected us, and protected society, by ensuring our location was known at all times and a minuscule transponder inserted into the brain where it couldn't be cut out by a misfit with a penknife and a high pain threshold. Why did the new machine race bother to keep humans going at all, but supplying medical services and food for example, and keeping going the facade of a human society? If you think modern human society is relatively well-ordered, a machine society would be ordered, predictable and boring. Humans present a challenge and introduce randomness into the equation. Coping with humans is a complex mathematical problem that gives machine life a meaning. They hadn't anticipated an evolutionary arms race though, and the humans with mental powers (well I could hardly be the only one, could I?) had altered the equation and presented them with a new set of puzzles to solve. That's why I'm still here.

They want to study how new-humans react. So each day I get plugged into this damn virtual reality interface and presented with situations so that they can "evolve" responses. Only I'm not playing their game. Each session, they try to provoke a response. I let them "kill" me. It perplexes them. It goes against everything they know about human survival instincts. It's only virtual reality after all. Active resistance in the real world didn't work, but maybe passive resistance in the virtual one will. I'm not badly treated and I figure that I can stall them long enough that maybe one of you can change the balance in favour of humans again.

Out in the real world, can you tell which of the faces around you are real and which have a mess of electronics under the skin?