Melisa had hired caterers, so there was nothing for me to do, except experiment with Rover and the ideas Jake and I had dreamt up.  The looks she gave me, periodically checking into my workshop, suggested I was failing at something.

"I've laid out a nice blue shirt and fawn chinos on the bed for you."

"Okay, thanks."  I would rather pull out all my teeth than go to this party, even in my own home, but Jake needed a mother-figure.  I approached the evening as I approached my work.  I needed to engage certain underused circuitry for approximately four hours, before I could cry off and say I was tired.

The first guests turned up at seven, and the women kissed me on both cheeks, and wore enough perfume to pull down big game, and the men wore nice blue shirts and fawn chinos.  At least Bill was here, an old friend who had gone into programming while I stuck with minimal, stimulus-response robots.

"Howdy, Jake," said Bill, and he dropped a cowboy's hat on the boy's head.  "Just got back from Texas.  Doing some work in the oil business now."  Bill rubbed his hands together.  "You've grown, you're going to be as tall as your Dad."

The house filled up with guests, mostly Melisa's friends of course, but I didn't mind.  She steered me around the place introducing me to what seemed to be clones of a common template.  Perfect teeth, tanned, monogrammed shirts, probably dentists like her ex-husband.  Then she introduced me to a tall stooping man with the air of a headmaster.

He pumped my hand.  "At last I get to meet the famous inventor of the Brainbots," he said.  "I'm sure you've saved me, and millions of others, from a fate worse than death.  You know, I used to have trouble with names, and losing my keys, and going out of the house on an errand, only to forget what I had gone for."  He beamed at me, eyes alive.  "Now I'm a Sudoku champion, and learning the violin."

"I'm glad the bots have worked for you."  No more neurofibrillary tangles, no more amyloid plaques; the brain circuitry of the elderly was no longer a battlefield.

"I understand that your son shares your interest in robotics."

"He's doing fine, but he's young and more interested in soccer, and how much ham he can pack in a sub."

"Mr Goodwood is keen to talk to us about Jake's education," said Melisa.

I wasn't keen, so I looked at my shoes, my dependable brown suede shoes that no-one would ever get me to change.

Another over-tanned, over made-up dolly appeared in front of me.  "Will you show us some of your robots tonight?"  she asked.  "I just loved the flying ones on TV."

I waved my hand around the room.  The conversation fell away.  "They're all here," I said, "waiting to come out."

The guests looked around the room, at their feet, at the ceiling.  Then one lady gave a sudden scream and there was a snap and a crack.

One of the robots had gotten under her feet.  I knelt down and picked up the broken pieces.  "Not to worry, it's my simplest design, easily repairable.  Just a cheap motor, a little candy tin and a battery.  The legs are piano wire.  I call it the pond skater.  There's another one over there."

A small robot, with four long spindly legs, shimmered across the floor like the eponymous insect.  "It uses nothing more than a motor to vibrate its body.  The vibrations are transmitted down the legs, and it moves, following the contours of the floor."

The guests were delighted, and more careful where they put their feet.  Most went outside to sit or stand around the swimming pool.  Melisa seemed pleased with me, although I avoided the tall stooping man, who I'd decided was Disney's child-catcher.  I got the feeling Melisa was building up to some major announcement, which we certainly hadn't discussed, so I felt tired earlier than I expected, which was a shame as I had just taken out Rover.  The hubbub drove him to find a hiding place immediately, and I guessed he would be safe for the night.

Jake was still awake when I went up to bed.  "Did you like the ice cream?" I asked.

He nodded, and I could see that the photo album had been open by his bed.  "They'll all be gone by morning, then we can go out and play ball." 

The boy was asleep moments after I kissed his forehead.

Limousines and chauffeurs came out in the moonlight and I watched from my bedroom window as they picked up the guests and took them up away.  Melisa click-clacked up the stairs, and I was asleep, or so it seemed, when she got into bed.  She seethed for a minute or two then got up again and went downstairs.

I lay in bed and listened and did some calculations about solar energy.  I wondered if Rover would be able to charge off the incident moonlight, even with the super duper new batteries I'd installed.  I got up and peeked out of the bedroom window.  Rover was sat on the lawn next to the sundial, solar panel absorbing the limelight, like a good photovore.

Seventy percent of the planet's surface is covered with water.  It surprised no-one that I suggested seventy percent of the garden should be taken up by a swimming pool.  Cobalt blue is the colour of the water in the day, under the California sky, and royal ink the colour at midnight, lit by underwater spots and the room lights of the house.

I heard the splash as Melisa dived in.  She swam a lot at night-time.  She said it eased the stress of her life.   I think she meant dealing with me and Jake.  She wasn't good with kids.

I realised where I'd seen the tall, stooping man before.  In the inside cover of the school brochure in her half of the bathroom: Priory Grange Prep School gives the best education to the most able boys.  A boarding school, much like the one I attended from the age of eight.  Priory Grange was fifty miles away, in another county.  It isn't a loving thing for a parent to do, in my humble opinion.  It could make a boy highly introverted and more interested in automata than people.

Jake was ten, sporty and sociable.  One day he would crack decimals and fractions, but I didn't hold my breath.  I liked the idea of the public school down the road.  Then Jake would be near us.  Melisa apparently didn't like that idea. 

I heard splashes from the pool and hung my head out the window to watch.  Melisa was swimming naked, which was an attraction in the early days, of course it was, but now things seemed to be different, four years on.  Her behaviour seemed to have jumped from one set of impulses to another.

Another, larger splash, as she dived in off the high board.

At the sundial, Rover startled at the noise and began to seek cover.  He paddled across the grass heading for the dark space under the stone bird table.  He passed Melisa's casually flung dress, set there in full view to tempt me down to the pool, but I wasn't playing ball tonight.  I knew exactly how she worked, and I knew how weak I was.

Rover walked past the dress, and then did a remarkable thing; he stopped, turned around and went back to the dress, twitching his front end as if sniffing.

I looked at the layout of the shadows on the grass, and at the umbra and penumbra thrown by exterior lights.  What did he see?  What combination of light and dark?  I would have loved to have probed his circuit boards with my multimeter.

Something else was going on.  Rover was now moving slowly away from the dress, searching left and right like a dog tracking a bird in high grass.  He ignored the edge of the lawn, and fell six inches onto the rubber pimpled path around the pool and kept on going.

I was alarmed.  Rover's edge detection circuit had failed.  Rover usually followed edges faithfully, like an insect following the edges of a leaf.  If there was a drop ahead of him, Rover would stop and back up.  He had LED sensors under his belly that detected the returning pulses from an infra red transmitter aimed downwards onto the travelling surface.  If Rover met an edge, beyond which was nothing, as in the top of the stairs in the house, the IR pulses were lost, and the motor stopped.  One second later, an electronic neurone fired to reverse the motor, backing Rover away from potential trouble. 

But on Rover went, apparently unshaken from his fall.  The little automaton was heading for a swim.  Was it the sparkling water, the confused jumble of light and dark, that attracted him?  It couldn't have been the sight of water streaming off Melisa's breasts that excited his neurons, because what I called neurones were not the specialised cells of men and adolescent boys, cells made of fat and salt and electricity.  Instead, Rover's neurons were circuits made of transistors, capacitors, resistors, op-amps, which relied on me to connect them in a specific order.

Melisa put out her hands to catch Rover, and I held my breath.

That giant body of water.  That not so insignificant voltage source in Rover's belly.  If the batteries were fully charged under the mad light of the moon, I rated them at ten volts.  It would be touch and go for Melisa.  Thirty feet by fifteen feet; depth six feet roughly overall, so twenty seven hundred cubic feet, at seven and a half gallons of water per cubic foot, so over twenty thousand gallons of water.  Not pure water, of course, it was treated with chemicals, and full of all the usual environmental debris: sweat, sun lotion, and other contaminants, so it was definitely not pure resistive water at ten meg-ohm centimetre or more.  The size of the pool might save her, but if Rover's batteries were sufficient to drive a current of even a tenth of an ampere around that giant circuit, and back to Melisa, then her heart would fibrillate and stop beating.

Rover stepped into the slowly lapping pool.  Melisa's mouth opened into a "no", and a question mark appeared over her head, and her very existence. 

I was right.  Melisa was as rigid and beautiful as a store window manikin waiting to be dressed in this season's outfits, and then she fell backwards in the water.  The pool lights blew out.

Rover was lost under the waves.  When I got down to the garden, Melisa was settled on the bottom of the pool, hair spreading around her like seaweed.

I thought about what to tell the police.  It was ten to two in the morning, officer.  I was awoken by the sound of a splash and the impression that the place was darker.  I realised Melisa wasn't in bed next to me, so I ran downstairs thinking something was wrong.  Of course, I checked Jake was okay too; he was sleeping in his room.  When I got to the pool, I saw her body under the surface.  I called her name.  I threw the life ring.  Then I got the long handled net we used for skimming the pool surface and pulled her up to the side of the pool.  I didn't even think about electricity. 

She wasn't breathing.  She was as floppy as a doll.  I tried to wake her, but it was no good.  I thought about CPR but I didn't know what to do.

There was movement across the floor of the swimming pool; a green discharge was emitting from the stricken Rover.  Green chromium sulfate, a positive test for ethyl alcohol.

I placed Melisa's dress to my nose; the silk was still high with the perfume she liked.  Evidently Rover liked it too.  I fished him out of the pool with the long handled net and held him in my hand, draining water from his body.  Where in the maze of circuitry had Melisa's scent excited him?  Why had he become so confused; had he been trying to choose the light on the surface of the pool, and the dark hiding place at the bottom?  Rover had no concept of his existence.  His zig-zagging route across the grass, and plunge into the swimming pool was not an act of self-negation.

A jury might decide it was an act of murder by robot.  But I could show them how Rover ticked.  Rover didn't have a microprocessor, or a brain, or any programmed instructions.  Melisa's Range Rover was smarter in that regard; it could do math better than people.  Rover was just a robot, whose circuits allowed him to respond to various stimuli in predetermined ways.  Just like us.