Little did I realise what a tart my sister in law Sally is. We don't usually holiday with them but this year, to save money decided to go together. We found a pleasant, secluded villa with pool in southern France, flying down and hiring a car. I'm happy to sit by the pool and normally just go sightseeing to keep Jane, my wife, happy. Sally is like me but Dave her husband likes to visit historic sites and take in the local culture. Great, he and Jane could go off, me and Sally could sunbathe , every one happy, 3 weeks in the sun. The first day we all just sunbathed and swam, walking down to the beach about half a mile away in the evening. I couldn't help notice that Sally, though about 10 years older than me, in her early 40's had a fit body, nice arse, good legs, quite small tits, short blondish hair. The first day she wore a bikini, catching me looking once or twice as she lay on her front by the pool, the top undone, the straps pulled down. The next day Jane and Dave said they were going out to visit a number of places and would be back about 7pm. They left early and I was drinking coffee by the poll when Sally came out. Wearing a triangle tied bikini top and a sarong. She got a coffee asking if I minded her going topless. Off it came revealing a pair of small firm tits tipped by hard little dark nipples. With her back to me she undid the sarong draping it over the lounger. My prick nearly burst out my shorts, all she had on was a g-string splitting the globes of her arse and when she bent over, the string disappeared in her cunt gash, parting her prominent, pussy flaps which hung either side. She settled on the lounger than called over, asking me to apply sun oil. I suggested she turn over so I could do her back but she replied "It's my front that needs attention", as she poured oil onto her legs then on to her tits letting it run down over her stomach towards her pussy. I knelt beside her and rubbed some in to her legs and shoulders. She took my hand and placed it on her chest, "You've missed my tits, you wouldn't want me to burn them would you?" a challenging look in her eye. Her nipples hardened under my touch and her breathing quickened when I moved to her stomach, moving my hand in circular movements, getting closer and closer to the tiny scrap of material covering her pussy. My fingers touched the material and she gave a small shudder, parting her legs slightly. I felt her hand on my thigh, stroking and slipping inside my shorts. My prick was rock hard when I moved my hand to her thighs, closer and closer to her pussy. I touched the strip of cloth, it moved in her gash, she lifted her bum and said, "Take it off". I pulled it down as she spread her legs wide. Her cunt was already wet and open, shining and pink, shaved except for a landing strip of trimmed pubes, ready for a hard cock. She was tugging at my shorts, pulling them down, taking hold of my prick. Getting my head between her legs I lapped her sweet cunt juices, sucking her clitoris as she slowly wanked my cock. She had her other hand on the back of my head, pressing my mouth harder against her cunt, thrusting her hips against my tongue. Then she stopped and just said "I want you inside me. Fuck me". She stood, spread her legs and bent over the lounger so I could take her from behind allowing her to wank her clit at the same time. I slid my cock in her, fucking her in a steady rhythm, slow then faster, deep then just the tip, feeling her fingertips frigging her cunt. She shouted out she was cumming and wanted to feel me spunk inside her to splatter my cum in her cunt. A few more hard thrusts and she had my load. We fucked three more times before Dave and Jane returned and that night after Jane had gone to sleep I heard them arguing because her tits were a bit sun burnt, she had obviously been sunbathing topless in front of me, he said and he was not happy about it, I don't know what she said but she didn't stop going topless or bottomless if they went out. They must have made up because soon I could hear them shagging, little did he know. We fucked about every other day, including anal, she loved to take it up the arse telling me Dave wouldn't do it. Twice she went off to the local beach when Dave and Jane were about, no chance of a fuck and I decided to follow. She went to a beach bar and was soon talking to couple of young lads who work in a restaurant we used most nights who couldn't have been more than 18 or 19. After a drink they went along the beach heading to a deserted area near some dunes. They disappeared from view in to the dunes, I hurried to follow then moving quietly hid behind some scrub bushes and grass where I could see them. She was already naked, sucking cock, kneeling astride the other having her cunt licked out. She looked a right slut, a forty something woman sucking teenage cock astride anothers head. She was soon grinding her cunt on his face sucking the cock deeper and faster until she took his load in her mouth, swallowing the lot. She slid down the others body, reaching between her legs to guide his stiff waiting prick into her gaping hole, then bounced up and down his pole as he thrust into her until she came and he spunked in her cunt. Since returning home I've fucked her 2 or 3 times but I'm not the only one, she's so cock hungry I think there are probably 5 or 6 others. Husband Dave seems to be totally oblivious to her extra curricular fucking and the fact he's married a slut.