The dynamics of the relationship between mother-in-law Mary Quinn and her son-in-law Tony Parkin had changed dramatically after Mary first suspected and then got confirmation that Tony had an interest in her knickers. His interest had started with him just touching clean knickers in the drawer in Mary's bedroom but he had then progressed to worn knickers and had ended up ejaculating whilst stroking his cock with knickers from her wash basket.

Mary discovered the spunk-splattered knickers in her wash basket before Tony could retrieve them and dispose of them. He had panicked at first when his semen started spurting and, after a bit of desperate washing, had put them at the bottom of the basket. He then thought that he would retrieve them later but never got the chance.

Mary's first inclination was to confront Tony about it whilst her daughter Susan was there but she did not want to hurt Susan so she waited until she had left the room before telling Tony of her discovery. Mary then itemised what was to happen to Tony, starting with him wearing some of Mary's clothing and makeup, then getting a severe hairbrush spanking, then worshipping Mary's arse, then giving Mary a fucking.

All those things were carried out but at the arse worship and then fucking stages, the balance changed a bit from Mary being in total control to Tony gradually taking charge and having total control during the fucking with him being rather good at pleasuring females.

They both wanted to fuck again but Tony said that next time it would be Mary taking the spanking, something to which she did not object. It was very important from both of their perspectives that Susan knew nothing about what had happened and what was intended to happen. Mary had a husband, Peter, but he was often out golfing or fishing and he had next to no interest in Mary or what she did.

Tony had to make sure that Susan, with whom he had a good sexual relationship, did not see his bare backside until the evidence of the savage spanking had disappeared.

In Susan's presence, Mary and Tony had to act as before, which meant that Mary virtually ignored him and if she did actually speak to him, it was usually in a disparaging way. Tony smiled inwardly when Mary was insulting him as he was thinking of when he would have her over his knee with her bare arse at the mercy of him and the hairbrush.

Mary and Tony were longing to get together again soon and Peter was having a few days away with a mate fishing, so it was just a question of getting a few hours together without Susan. Things fell into place for them when Susan told Tony that she was going into the city for the day the next day with her friend Cathy. Susan had already told her mother; she tended to tell her mother things before she told her husband.

Tony's job meant that he often worked from home but his hours were flexible. He was anxious to get in touch with Mary at the earliest opportunity, as she was with him. Normally there was virtually no direct contact between Mary and Tony, although they had each other's mobile phone numbers.

With Susan out of the room, Tony sent Mary a text. 'Have you heard from Susan?'

'Yeah, we can fuck,' came the reply from Mary.

'and I can spank your arse,' responded Tony.

'Ha almost looking forward to it,' Mary replied.

'What time shall I be there?' asked Tony.

'As soon as Susan has gone, I want you,' replied Mary.

'See you tomorrow, you horny bitch,' typed Tony.

'Cya,' replied a turned on Mary, so turned on that she promptly had her skirt and knickers off and masturbated. She smiled to herself when she put the knickers back on her soaking cunt; Tony would like them.

The next day dawned and Mary was exhilarated. She looked forward to the fucking that she knew that she would be getting; she was less sure about the spanking but thought that even that might be exciting.

Tony, meanwhile, looked at his wife, who he loved very much, and felt guilty that as soon as she had gone he was going to be having hours of sex with her mother. He cringed a bit when Susan was about to go and she smiled sweetly at him. "Bye, baby, be a good boy," she laughed; although she did sometimes inadvertently talk down to him, her mother did it on purpose.

"I will, you have a nice day with Cathy," replied Tony, hoping that Susan could not see the guilt in his eyes.

Susan left and Tony felt so guilty he decided to call the get-together with Mary off, he phoned her mobile. "Mary, I can't do this, I feel so bad about deceiving Susan," said Tony.

Mary thought for a moment before responding. "Tony, you know that what we did only came about because you could not keep your filthy self away from my knickers," replied the calculating Mary, who was able to ignore her own feelings of guilt regarding her daughter and her husband.

"Yes, I know that," replied Tony, wondering where Mary's thought process was going.

"After we texted each other yesterday I frigged myself then put my knickers back over my sticky cunt; those knickers are here waiting for you, Tony," said Mary, in her best seductive voice.

"But Mary, I don't like deceiving my wife," pleaded Tony, who was torn between what he wanted to do and should do.

"Is your cock hard, Tony? Are you erect?" asked Mary, continuing with her seductive voice.

"Fuck yes, my cock is hard, you sexy bitch," snapped Tony.

"Well, come around here and give me a good fucking," said Mary, smiling as it looked like she had won him over.

"Not until after I have spanked your fat arse," retorted Tony.

"Yes, give this bitch the spanking she deserves; tan my fat arse," agreed Mary.

Tony's response was incoherent before the phone went dead but Mary felt safe in the belief that later that morning her son-in-law's twenty-six-year-old cock would be in her fifty-eight-year-old cunt. She also knew that she was likely to have a very sore backside before that happened.

With the two homes only a few streets apart, it was not long before Tony arrived at Mary's house, his mind still in turmoil but his penis looking forward to what was soon going to be happening. Mary opened the door and almost dragged him indoors before locking her lips on his. Mary's hand went to Tony's crotch and felt his bulge. "Oh yeah," said Mary, her eyes flashing.

"Where are those knickers you told me about?" asked Tony, still fighting with himself mentally.

"Top of the wash basket, just where you like to find them, you pervert," smiled Mary, a sexy smile.

Tony felt disgusted with himself but he also felt so turned on. There was so much he wanted to do, and all at the same time. He wanted to get at his mother-in-law's worn knickers, he wanted to spank her arse, he wanted to fuck her cunt.

Tony did not speak but went up the stairs; Mary, with a smirk, followed him. Tony went to the bathroom and the wash basket and Mary watched from the doorway as Tony took a pair of green knickers from the top of the pile and examined them.

"See, told you I put them back on my cunt after I orgasmed; why don't you put them on, Tony?" said Mary, licking her lips. Fuck she felt horny, as did Tony.

"I will, and then I will tan your arse," said Tony, getting his voice back.

The couple had their eyes on each other as Tony slowly removed his trousers and then his briefs, his erection sprang out and Mary almost swooned. Tony then put his mother-in-law's worn knickers on; they felt wonderful to him around his rigid cock.

"You get your arse bare, I am going to turn it red," said Tony, talking to his mother-in-law in a way that he would never have even dreamed of doing just a few days previously.

"Oh, bare arse straight away; okay," said a surprised Mary although she thought that it might mean that she got fucked sooner.

They went into the bedroom and, with her back to Tony, Mary removed her skirt and knickers. She smiled back over her shoulder as her bottom became bare. "You like my bum, don't you, Tony?" she grinned.

"It is a wonderful bum but it is going to be a sore one very soon," said Tony, moving the position of the chair in Mary's bedroom.

"I hope that you kiss it better afterwards," pouted Mary. 

"Oh yes; now bring me your hairbrush," said Tony, seating his knicker-covered backside on the chair.

Mary picked up her hairbrush and moved towards Tony, her eyes moving from Tony's eyes to his erection, which was causing her knickers from the previous day to stretch. She handed Tony the brush and lay over his lap and they had to adjust positions a little bit to get his rigid penis in a comfortable place for both of them.

Tony lovingly caressed Mary's arse cheeks and she parted her legs a bit as she felt an added tingle in her vagina. "Going to spank your arse now," warned Tony before commencing smacking the hairbrush down on Mary's buttocks.

CRACK CRACK CRACK CRACK sounded as the brush went from one cheek to the other and Mary squirmed as her buttocks started to turn pink. Tony spanked on and on, possibly not quite as hard as he could but hard enough, and Mary bucked as CRACK CRACK CRACK CRACK landed on her backside.

This was a situation that would have been considered impossible a short while previously, before Tony's interest in Mary's underwear got discovered. The spanking went on and Mary's arse was glowing and she was twisting violently as her buttocks caught fire. She was in mental conflict, both wanting it to stop but also finding it exhilarating.

Tony stopped the spanking and then stated the obvious. "Now you have got a sore arse," he said, as Mary sobbed over his lap.

"Yes, will you kiss it better for me, please?" asked the mature woman who was still sprawled over the younger man's legs.

"Yes, get on your front on the bed," replied Tony and Mary got off his lap and lay on the bed.

Tony had leaked precum into the knickers that he was wearing but had not ejaculated, as he had when receiving the spanking. He knelt to Mary's left side and softly kissed her well-tanned left arse cheek; he then kissed the right one. He then moved so that he was between Mary's legs, which she opened wide, and he then did some more buttock kissing.

Tony then put a finger in Mary's arse crack and slowly ran it up and down. "Oh fuck, Tony, that feels good," muttered Mary. Tony inserted a second finger and Mary squirmed as her son-in-law played her arse crack. Tony then shifted again so that his still-knicker-enclosed erection was touching Mary's butt crack, and that sent her even more wild.

As Tony dragged his erection up and down her crack, Mary came. "Fuck, oh shit, oh, oh," Mary wailed as she orgasmed.

Tony decided that now was probably a good time to get his cock free so he stood up and removed the knickers as he looked at the convulsing woman on the bed. "Fancy a fuck now, Mrs Quinn?" asked Tony.

"Shit, do I? Give me a long hard fucking," smiled the fifty-eight-year-old whose arse was still burning from the spanking.

"Get up on your knees, I will start from behind," instructed Tony, and Mary complied.

Tony eased his large cock into Mary's wet cunt and she pushed back, taking him further in. "Oh yes, fuck me good, young man," purred Mary as her cunt took Tony's whole length in.

Tony held his penis all the way in for a moment before very, very slowly almost fully withdrawing then equally slowly sliding in again. "Shit, oh fuck, mmm," uttered Mary as she became aware that she was very likely embarking on a sensational fucking.

A sensational fucking it was as Tony gradually increased the speed and force of his trusts and his mother-in-law squealed in delight. "Cumming, fuck, oh fuck, cumming," Mary wailed as she marvelled at the lovemaking abilities of her daughter's husband.

Tony enjoyed having this power over Mary but he equally enjoyed giving her the pleasure that he was giving her. He continued to shaft her from behind for quite a while before moving her so that she was on her back with her knees towards her tits as he fucked her hard from the front. Both Mary and Tony were still clothed up top and their clothes were now wet with sweat as the sex continued.

Tony's cock moved rapidly in and out of Mary's cunt as her thighs and arse crack got soaked by her cum. Tony was grunting and groaning as his ejaculation approached. He looked into Mary's eyes and panted a compliment. "You are a great fuck, Mrs Quinn, and a fucking sexy woman," said Tony as he felt his spunk rise.

"Shit, oh fuck," was all that Mary could respond, as she felt Tony's cum blast into her and ignite another orgasm.

When their bodies eventually relaxed and they got their breath back, Mary paid Tony a compliment. "You certainly know how to give a woman a good fucking," said Mary before she kissed Tony passionately.

"That is probably the nicest thing that you have ever said to me, Mrs Quinn," smiled Tony after the kissing stopped.

"Yes, you are probably right; must not make a habit of it, or maybe we should?" laughed Mary in response.

It was incredible to think that until so recently Tony only ever addressed Mary as Mrs Quinn because that was all he was allowed to address her as. Now they were lovers and had each given the other a good spanking.

At Mary's suggestion, they removed their remaining clothing and showered together. Tony paid Mary's impressive tits some attention for the first time as he cupped them as his hardening penis pressed against her arse as the shower water cascaded on them. Mary then turned and they kissed as Tony gently caressed Mary's recently spanked buttocks.

"I want to suck your cock," announced Mary before dropping to her knees in the shower and taking Tony's now fully erect penis in her mouth. She sucked him and licked him and used her hand on his balls and to wank him. Tony let her take him closer and closer to spunking again.

"Oh Mary, I am going to cum," Tony warned but that only made Mary increase the speed of her tonguing and wanking.

Tony started spurting in Mary's mouth and she would have happily tried to swallow it all but she took her mouth away with a giggle and took the rest of his cum on her face and in her hair. When they eventually left the shower, Tony had his head in between Mary's legs on the bed and tongued her to another orgasm.

They had had great sex together but whether they would continue their affair, they did not know. Their relationship had certainly taken a dramatic change, but they had to hide that change from Susan.

That night, with Susan back from her day out, Tony again felt guilty. He truly loved his wife, but he loved fucking his mother-in-law.