"Of course," he murmured, ruffling my hair with his right hand and stroking his fingers across my bare neck, sending shivering spasms of anticipation down my spine. "What Harriet craves," he continued, talking over my head as though I were some dumb animal, "is public humiliation. Yes, she's my slave girl, and she'll do anything I ask of her. We both take that for granted, and it's just a part of our normal life, like having toast for breakfast or going out on Friday nights. That's just the way it is. But what she really needs is to have that subservience exposed in public, and the more humiliating it is the better."

"Hence the naked picnic," the stranger said.

"Just so. Harriet got really turned on by the fact that someone could come along and catch her naked. And then, of course, you did. Can you imagine how much that turned Harriet on?"

"Did it?" the stranger asked me. I nodded mutely, my eyes lowered in shame.

"And so if I'm to prove all this to you, I need to choose something totally shaming for Harriet to do." He paused. "Don't I?"

"Yes," the stranger said, her breathless voice betraying, I suspect, her own excitement.

"Something to show how obedient little Harriet is. How well trained she is. How eager to please." My Master bent down to where the stranger's labrador was lying and picked up its ball. The dog stirred curiously but saw its Mistress standing impassively and resumed its prone position.

"Just like your dog, in fact," my Master continued, staring into my eyes. "Harriet's like my own, house-trained puppy. Aren't you, poppet?"

I nodded.

"And of course, all little doggies like to chase things. They like to fetch, don't they?" He spun the ball round and round in his hand as he spoke, casually flicking it a couple of inches in the air and catching it again. Neither the stranger nor I spoke.

"So that's what we'll do, I think. Harriet, fetch girl, fetch." He swung his arm and threw the ball hard. It ballooned over the river, arcing to a zenith just beyond the midpoint of the water and descended in the light vegetation behind the path on the opposite riverbank, rolling slightly and disappearing out of sight. The stranger's dog, seeing its ball despatched, made to set off in pursuit, but my Master held its lead and prevented it from moving; the dog barked loudly, but remained where it was. My Master turned to me.

"Well?"

"Master?"

"Fetch the ball."

This couldn't be real. I was naked, and my Master was making me run and fetch a dog's ball from the other side of the river. Tears coursed down my cheek as I contemplated what was expected of me.

"You can put your trainers on. But I'd hurry. I can see some people coming." I looked down the river and saw, to my horror, that a couple were walking up the opposite bank in the direction of the ball I was expected to retrieve. They were still some distance from it, but I would have to move fast to avoid them.

Panic took over and I hastened into my trainers, frantically sliding them over my heel and loosely tying them. I got to my feet unsteadily, my legs shaking with fear.

"And Harriet," my Master said slyly. I knew that tone, and knew there was to be something else.

"Yes, Master?"

"When little doggies fetch balls, how do they carry them?"

I looked at the stranger and she returned my shocked look. Earlier, I had thought she was dealing with this peculiar turn of events with élan, but now she was looking distinctly uncertain of herself.

"In their mouths," I replied.

"Exactly. Off you go then, Lassie." That stung, being called Lassie, being compared to a dog. With a nervous look back down the river at the progressing couple, I took off in the opposite direction. Instantly, as I began to run, the feeling of the wind whipping against my bare skin made me feel even more exposed and self-conscious. I felt that the whole world could see me, could witness my humiliation as I ran in pursuit of a dog's plaything.

I headed up the riverbank towards the neat, wooden bridge about fifty yards away, stumbling over some of the loose stones and praying that I wouldn't lose my balance and fall over. I reached the bridge and stepped onto it warily. Until now I had been able to skirt close to the edge of the track, where the trees and bushes managed to partly conceal me. Now, however, I had no cover. I looked around anxiously and noted that the couple were getting closer, but at least Icould not see anyone else. Holding my breath and summoning up my courage, I struck out and crossed the bridge, my feet clattering so loudly on the wooden slats I felt sure that anyone within half a mile would hear.

I reached the other bank and without pausing ran as fast as I could to where my Master had thrown the ball. I knew I was going to have difficulty finding it, as it had landed in the greenery. My body was tingling, the cool air wafting against my breasts and pussy and eliciting, despite my terror, a tingle of sexual excitement. I was running in the direction of the unknowing couple, still perhaps a quarter of a mile from them, and I knew that it was inevitable they would spot me sooner or later. Curiously, that realisation galvanised me and, knowing I had no option anyway, I ignored them and concentrated on the task in hand. I was directly opposite my Master and the stranger now, and knew I was in the right vicinity.

Bending over and giving my Master and the stranger an unintended full flash of my behind, I began to scour the light shrubbery behind the path. There was no sign of the ball, and my search became more and more frantic with every passing second. The couple were getting closer, and I was sure that they had now spotted me. Please, dear God, I thought, please let me find the damned thing.