It was Friday night, a few weeks after I had comprehensively fingered my stepdaughter, Hannah, that extraordinary evening in the hot tub. I had arrived home from work unexpectedly early; my meeting in London having ended sooner than usual and I had been able to catch an earlier train.

Haunted by guilt and the fear of exposure, I had been avoiding both my stepdaughter and the tub ever since that night. Unnervingly, Hannah had been behaving as if nothing had happened - though it was obvious she now believed we had a shared secret - and I was just starting to feel safe.

But I still hadn’t dared use the tub with either Hannah or her mother, my wife, Debbie.

The house was empty; Debbie was meeting colleagues after work and Hannah was going to a movie with a potential date so I could do whatever I wanted without interference.

What I wanted to do first was go on a run through the ancient woodlands that our house backed onto - the warm late August sun was shining so brightly it was simply too perfect an opportunity to miss - so after quickly changing into my vest and shorts, off I went.

An hour later, hot and sweaty but feeling content and very righteous, I jogged panting into the back garden and tried to regain my breath while cursing myself for not having trained harder for the past few months. The run had been everything I had wanted; warm paths, cool shade, the smell of the trees; perfect! Opening the back door I quickly grabbed a cold drink from the fridge before going back outside to rehydrate and cool down.

My eyes were inevitably drawn to the hot tub that bubbled away almost silently in the corner of the patio and the idea of having the sweat and dust on my body washed away and my tired muscles gently massaged by the water grew more appealing by the minute.

I went back into the house and grabbed a towel from the laundry room then slipped off my running shoes, socks and vest before returning to the tub dressed only in my running shorts. I knew I should have had a shower before getting into the water but it looked so inviting, I felt hot and sweaty and there was no-one to see me. I just couldn’t resist it and stepped guiltily into the water, panting a little at its temperature then lowered myself up to my neck in its hot depths.

It felt simply wonderful as my body adjusted to the heat; the calming, soothing liquid enveloped my tired, aching muscles, its warmth making me almost dizzy with the sensations. I sat on the submerged bench, leaned back against the smooth side, spread my arms around its edge and tilted my face towards the clear blue sky.

Relaxation washed over me. Alone in the house, out of earshot of the phone, invisible to the neighbours and feeling pleased with myself for having got the day’s exercise out of the way, I washed the salt from my face and pressed the button beneath my fingers.

The bubbles started. I could feel the powerful water jets pummelling my legs, lower spine and shoulders, easing the strain my woodland run had induced. I sipped my Diet Coke, wishing it had been a cold beer instead, closed my eyes and let myself drift into a doze.

The weekend was coming; Anne and Ted’s barbecue on Saturday; walking in the countryside on Sunday...

“Pfffft!” The sound of a drink can being opened snapped me back from my reverie with a jolt.

“Hi!” Hannah’s voice coming from behind me was soft and friendly. “Fancy a beer?”

“Hannah!”

I jumped with surprise, my head turning first left then right in a futile attempt to see where the voice was coming from. My awkwardness made her giggle as she walked round the tub and into my field of view.

My tall, skinny stepdaughter had changed into the smallest bikini I had ever seen – mere scraps of dark blue cloth held together with dark blue strings and bows. There was no way her mother would ever have bought it for her. Fortunately her breasts were so small even this inadequate piece of clothing could contain them but I still felt uncomfortable.

“Like my new Bikini?” she asked, amused. “Better not tell Mum, ok?” she added in a conspiratorial whisper as she replaced my warm flat Coke with a can of cold beer and lowered herself gently into the water opposite me.

“I thought you had a date,” I said, slightly annoyed at the interruption and feeling rather nervous.

“I just cancelled,” she replied as she sank beneath the water, looking me straight in the eye.

She leaned back until just the tips of her barely-covered nipples were visible above the foam. To my horror I could see they were erect.

“You’ve been avoiding me,” she said accusingly once she had settled herself on the low bench.

The bubbling water just covered her bikini top which saved me a little of my embarrassment.

“What makes you think that?” I asked, spinelessly answering a question with a question.

She gave me an exasperated look.

“I’m not a child anymore. I thought we had... something special between us.”

By now my cock was rock hard and painfully tangled in my running shorts. I fidgeted beneath the bubbles trying to free its constricted end without drawing my stepdaughter’s attention to my discomfort.

“Hannah, that was a mistake,” I replied, trying to sound like a parent and not like the rather frightened, turned-on teenager that I felt like. “I shouldn’t have...” I ran out of words.

“Shouldn’t have what?” she asked aggressively. “Shouldn’t have fingered your stepdaughter?”

“Hannah!”

“Well that’s what happened isn’t it?”

“I didn’t realise what I was doing,” I protested. She laughed.

“From here it felt like you knew exactly what you were doing!”

Her green eyes sparkled with mischief and something moved between my thighs. I quickly tried to close my knees but was too late; Hannah had stretched out her leg until her right foot was pressing against my crotch, her toes firmly against the erection that I now couldn’t hope to hide.

“That’s better,” she said, wiggling her toes against my shaft. "I thought you might be hiding something from me. Now we don’t have to pretend.”

“Hannah, I...”

“Don’t worry!” she interrupted. “When I told you everything was okay, I meant EVERYTHING was okay, okay?”

Her toes wriggled again against my cock which was now bent painfully in my shorts.

“Except it isn’t okay anymore because you don’t want to be with me.”

The toes worked their way beneath my tight scrotum.

“Why are you doing this, Hannah?” I asked, for some reason quite unable to do the simple thing and push her foot away from my groin.

“Don’t you like it?” she asked archly. “It feels as if you like it.”

She wiggled her toes against my erection again.

“Hannah, please...” I began but there was no conviction in my voice.

“It’s only fair,” she continued, her foot falling away from my groin.

She slid forwards in the water until she was on her knees in front of me, the bubbles reaching her small breasts, her hands replacing her toes on my erection.

“After all, if it’s okay for you to touch me, then it should be ok for me to touch you, shouldn’t it?”

“Hannah I...”

“Or don’t you think Mum would agree with that?”

The implied threat was obvious but belied by her eyes which were sparkling with mischief. I felt her fingertips slide underneath the elastic waistband of my shorts, pulling them down a few inches, allowing the head of my almost fully erect cock to poke out of the top.

“Stop!” I croaked in surprise.

My hands flew to my groin in an attempt to cover myself but she was determined and a moment later I felt her slender fingers closing around the upper half of my exposed shaft. A surprised, uncertain expression crossed her face but whatever thoughts were causing it, she seemed to fight them away and I felt her grip on my shaft tighten.

“Fair’s fair, Daddy,” she said softly in a voice quite unlike her normal tones. “It’s my turn now – I’m sure Mummy would agree.”

“Hannah I didn’t...”

“Oh yes you did, Daddy. You definitely did. And now it’s my turn – unless you’d like to ask Mummy first!”

She brushed my helpless hands away and began to run her fingers inexpertly up and down my erect cock. She was clumsy and unsure with a slightly puzzled expression on her face as if touching one for the first time. Though that idea didn’t come to me until much later.

Whatever her skills might have been, my body didn’t complain and within seconds my cock was fully erect, awkwardly tangled in my shorts. Hannah’s fingers delved deeper between my thighs as if exploring a man’s body was a new and exciting adventure. She frowned as my shorts frustrated her progress.

I felt her fingers leave my cock and slip under my elastic waistband. There was a short sharp tug, then another, then she looked me straight in the eye.

“Lift up!” she grinned.

“Hannah please!” I began. “We shouldn’t...”

“Shh!” she interrupted. “We already did, remember?”

She pulled again at my waistband. Like an automaton I lifted my bottom from the bench and felt my shorts being drawn down my thighs and over my knees and down until they tangled around my ankles beneath the bubbling water.

“There! That’s better!”

I felt very naked and exposed; my eighteen year old stepdaughter had just stripped me! Freed of its constraints, my cock burst out from the tangle of pubic hair at its base and stuck vertically upwards, already very hard indeed.

Hannah looked both puzzled and amused then I felt her little hands moving along my thighs until her fingers brushed against my shaft and took it once again in her fist.

Then to my astonishment, my eighteen year old stepdaughter began to masturbate me beneath the water, her slender fingers sliding awkwardly up and down my so-hard shaft. Looking back it was obvious that she had little idea what to do; she made no attempt to play with my smooth, swollen end or the tight sack between my thighs but it didn’t matter; the sensations were wonderful if bewildering. Indeed I became so aroused so quickly that, if she had done any more, I would probably have come straight away.

“Do you like this?” she asked quietly.

“God yes,” I replied breathlessly.

A huge glow of satisfaction crossed her pretty young face as she moved closer, her hands still on my cock then rose slowly to her feet in front of me, only releasing my erection as she stood upright with the bubbling water washing around her barely-covered groin.

Her smooth, skinny belly was only a few inches from my face, dripping with hot water; her pale skin slightly tinged pink which was as close as she ever got to a sun tan. She placed her hands on my shoulders and stood still, expectantly, her legs straddling mine.

“Take off my panties, Daddy!” she hissed into my ear. “I want to feel your fingers again.”

Stunned, compliant and with my heart thumping, I raised my right hand to her left hip and gently pulled the tail of the bow holding her tiny bikini in place. It resisted and she giggled. I pulled harder and, with a slight squeaking sound, the bow came undone and the side of her bikini fell away, revealing tantalisingly the top corner of her tightly curled triangle of fiery pubic hair.

“Now the other side. Please!”

I could feel Hannah trembling slightly as I raised my left hand and released the second bow. The tiny scrap of material fell away completely, floating on the bubbling surface of the water and leaving her vulva naked and glistening in the foam. My heart still pounded in my chest as I reached out for her waist with both hands, then ran my fingers down her sides, across her skinny tight buttocks and around to her flame-red triangle where I tangled my fingertips in the tight teenage curls.

“Are you sure you want this?” I whispered. My beautiful stepdaughter nodded slowly.

“I’m sure, Daddy.”

I slid my hand between the top of her pale, skinny thighs, feeling the warmth of her wet flesh against my skin. She was smooth and hot and incredibly arousing as she parted her legs to give me freer access once again.

I ran my middle finger gently and slowly along the length of her slit, feeling the heat from her body and the soft vulnerable folds of flesh concealed between her puffy, almost hairless outer lips.

“Mmmm!”

She moaned softly and I repeated the action, toying with her inner lips and finishing up with my fingertips either side of the hard nub of her clitoris. I squeezed it gently.

“Oh!”

Her hands tightened their grip on my shoulders and the sound of pleasure and surprise that escaped her lips made my erection surge yet further upwards. Emboldened, I began to toy with her tiny clit, running my finger along its underside then back between her thighs until I could dip my fingertip into her vagina.

“Yes... yes please...”

Unlike most of the girls I had fingered in my life, Hannah seemed to be getting more pleasure from her vagina than her clitoris so I plunged my finger deeper into her and began to work it back and forth as I had done that first amazing evening in that same hot tub.

She was tight; incredibly tight and I had to press hard to penetrate her body but I persisted until my entire middle finger was inside her, my palm cupping her fiery red triangle. I worked my finger around, curling it back towards her pubic bone in search of her g-spot, still amazed at how extraordinarily tight my young stepdaughter’s vagina really was.

Finally my fingertips found the small rough patch hidden within her and I began to stroke it, first slowly then with small, fast movements.

“Oh my God!”

Hannah’s already-trembling body began to shake as my fingers did their hidden job. Her hands were on my shoulders; I felt her fingernails digging into my flesh. The muscles on my forearm bunched and my fingertip moved faster and faster over her g-spot, her vagina still gripping me as tightly as I had ever been gripped.

“Daddy...Oh Daddy...” she moaned.

A tremor rocked her body as a small orgasm passed through her. I fingered her a little more and a larger tremor swiftly followed. I looked into her pretty face; her eyes were tightly closed and she was biting her lower lip as a third and much larger spasm rocked teenage body.

But this time I knew it wasn’t enough - for either of us.

Before she could get too sore, I slowed my fingering to a stop, feeling tiny aftershocks passing through her skinny body. Her eyes opened and I looked into their dreamy pupils anxiously.

“Do you want to... do it?” I asked softly.

My half-finished question was answered with a clear, unambiguous slow nod.

“I want to... do it!”

Sliding my fingers carefully from her vagina and taking her firmly by the waist, I turned my stepdaughter’s back towards me as I had done so many times with her mother. Naked from the waist down, Hannah’s half-hidden buttocks were pale and firm.

I steered her until her bottom was over my lap and slowly but firmly lowered her onto my waiting erection. I felt the heat of her in the water as her young vulva touched the sensitive tip of my cock which parted her inner lips as it slowly penetrated her lithe teenage body.

What should have happened was that she slid smoothly down my rock hard cock, forcing it deep into her hot waiting core until her soft buttocks nestled against my groin and my sensitive tip rested against her youthful cervix.

What actually happened was that, unsuspected by either of us, the water in the hot tub had washed away most of her natural lubrication and despite her spread legs, her tight body resisted penetration painfully. After half a dozen attempts at lowering herself onto my cock during which her inner lips were stretched and her clitoris battered, eventually she sat back hard and bent my erection almost in half which made me cry out in pain.

The tension now broken, and giggling her apologies, Hannah stood up in the water, turned around to face me and replaced her hands on my shoulders. A broad smile on her face, she lowered her lips to mine and we kissed. At first it was a simple peck, then a second, then a third then we dissolved into a full scale make-out kiss, lips wide open, tongues deep in each other’s mouths.

And as we kissed, I felt her knees moving either side of mine until she was straddling me properly. Without breaking the kiss and with judicious use of her supple, writhing hips, my anxious fingers and a lot more giggling, we managed to part her inner lips enough to let her ease herself onto my cock.

Our mouths froze and parted as, with some difficulty, the head of my cock entered her body.

The feeling of her incredibly tight, hot, slightly dry vagina sliding down over my painfully hard, half bruised erection for the first time is one I will never forget.

Biting her lip again, Hannah lowered herself slowly onto me, paused when the lubrication dried up, then rocked back and forth, raising and lowering herself until her wetness returned. Then she slowly continued her descent until her smooth, bony buttocks rested on my lap...