Looking back, it was all my doing. I should never have told Mike that I fancied Leanne, my wife's younger sister. In the four or five years I'd known Mike, he was always asking about Leanne, as though he got off on the little things I would mention about her whenever she visited. He'd never met her, and so would ask me if her tits were better than my wife's, Rachael. "Did she wear that skirt with the split right up the back again?" he'd enquire hopefully after I mentioned she'd come by the previous evening.

The truth was, Leanne has all the good bits that Rachael did, but she was 4 years younger and everything about her was that little bit better. They were both relatively tall at 5'9 and both had great legs. Leanne's boobs were slightly bigger than my wife's 34B, and she tended to show them off more. Her hips were an extra inch wider, but in that perfect place that accentuated the peachy curve of her arse.

Rachael was lovely, don't get me wrong, but next to Leanne, she looked average. And of course Leanne managed to pick outfits that showed herself off far better than my wife dared do.

"Have you ever fucked her?" Mike asked me once.

I had to admit that I had thought about it many times, but never had.

"Never had the opportunity," I said, knowing that really I meant, "I've never plucked up courage to try." The truth was that if I messed it all up, then perhaps I'd lose the two most lovely women in my life.

But the seed of that thought was always in my mind. I still saw Mike occasionally, and I always hoped that someday I'd be able to tell him I'd done the deed. Then one Easter something unexpected happened.

Leanne was visiting us over the holiday, she likes our out-of-the way house in the countryside with good views all round. Her flat in London is convenient, but she can hardly see greenery from any window. It was early evening and we were just deciding what to eat when there was a knock at the door. We weren't expecting anyone but I went to see who it was.

No sooner has I opened the door than a man in a ski-mask and balaclava-type hat shoved himself in and pointed a gun at me. He motioned me back inside and pushed the door closed with his surgically-gloved hand.

"What the fuck are you playing at?" I asked him, rather stupidly. It was quite plain he was robbing us!

"Shut up, do what I say," was all that he said, and I wasn't going to be a hero while I had a gun pointed at me. I backed into the living room where the girls were sat, wondering what on earth was going on. "Oh," the guy said, "a couple of hotties eh? Were you going to have threesome tonight?" he cockily joked to me.

Suddenly images of having both women flashed through my head, but I managed to stammer out "No, don't be stupid that's my wife and her sister."

Maybe calling the intruder stupid wasn't the best idea in the world but I just felt I had to deny the fact to my wife that fucking Leanne had ever entered my head. Ever. At all. My train of thought got seriously disrupted when this man switched his attention to Rachael and Leanne.

"Get your tits out then, let's see them". He waved the gun around to indicate what he expected to happen, as the girls both looked terrified at the weapon and stunned by his demand.

I pulled out my wallet and pulled out all the cash I had in there, "Look, just take my money and leave us, ok?" I offered, "We don't want any trouble."

He let out a long "Nooo, no," and seemed to relax a bit, "I think this is far better than your money, mate. Come on, let's see them." And, much to my secret joy, they both pulled off their tops and reached behind themselves and unclipped their bras. I was trying hard to keep my "pleading-protesting face" in place and also trying not to let my eyes linger on Leanne's gorgeous breasts for too long.

"Very tasty," said the guy, his voice still slightly muffled through the mask. He swapped the gun over to his left hand and reached out with his hand right, which looked comically blue in that latex glove and fondled my wife's tits. Then he did the same to Rachael. I saw a brief opportunity while his back was slightly turned to me to do whatever it is they do in the movies to disable an attacker with a punch to the kidneys... or was it a chop to the neck.. or a headlock...

"Which feels better to you?" he was suddenly facing me again, obviously heroics are split-second things not for thinkers like me.

"Eh?" was all I could muster.

"Which tits do you prefer?" he asked again, "Go on, grab a handful and see if we agree."

I shook my head in disbelief and stood in front of my wife and ran my hands over her familiar breasts, "I've no idea what he's on," I tried to say as quietly as possible to her, but she stood there like a bit of a zombie.

"Just do what he says," she replied.

Then I looked Leanne in the eye and gave her my best sorry look as I moved to give her breasts a cursory feel. Or that was my intention. Once I laid my hands on those fabulous orbs I'd fantasised about many a time, I just had to give them a proper squeeze and carressing, after all I didn't want this guy to think I was not following his orders.

"Well?" he asked, "Which ones?"

Shit, now I was torn, I looked between Rachael and Leanne, my wife and her sister, both stood there like manequins in this surreal situation than none of us could quite comprehend.

"Yeah, I like them smaller too," the guys said from behind me as I looked round. Cheeky fucker was only taking a picture with his phone! "What about their arses, I like arses best," he laughed. "Bend them over and lift them up," he elbowed me as he said it and nodded towards the girls.

In turn they looked at each other helplessly, and then to me. It was Leanne, as usual, who took took the lead and promptly turned round and bent over.

"Let's just get it over with, Rae, then he'll leave us alone," she whispered to my wife, who slowly did the same. With not a lot of prompting from the guy I lifted up both their skirts to show off their bottoms. It reminded me of a porn movie I'd watched a few weeks earlier of two naughty schoolgirls bent over ready to be spanked. Despite the wierdness that was now happening in our lounge I felt my cock throb with that memory.

"Pull their knickers down too, half way," urged our unwelcome guest.

I felt a strange rush of excitement, first at exposing my own wife's bare backside and lightly trimmed pussy to this complete stranger, but then at peeling Leanne's white briefs down to mid thigh too. Her peachy bum framed her totally bare pussy lips and I got my first look up close at something I'd been aching to glimpse for years.

I must have lingered a bit longer than I intended as I knelt there, as the phone was held close to my face and another picture was taken. "Have a taste, she looks good enough to eat, go on," the intruder urged. As I started to protest that I couldn't really, his hand pushed my head forward between her cheeks.

Leanne took a sharp intake of breath and I mumbled a half-hearted apology of sorts - both to my wife and to Leanne.

"Shut up and lick your wife's hole," I got gruffly told.

Rachael piped up from beside us "Actually, I'm his wife."

This got a throaty laugh from the man and a hidden smile from me as I tasted Leanne's pouty hole. God, I was doing something that I'd been wanting to do every visit Leanne had made to our house and now I was it was under these bizarre circumstances. I didn't know whether to curse my luck or thank it.

"Get your cock out and fuck her then," he laughed, at which point both girls started to stand up straight.

"Hang on a mo," both girls said in unison - it was one of their favourite phrases - but he was having none of it,

"Get back on your knees you two." I looked over at my wife as I unzipped my trousers and pulled them down.

"What am I supposed to do?" I pleaded with her, hoping she hadn't noticed I was already on the way to a healthy erection. I knelt behind Leanne and rubbed the end of my cock up and down her slit a couple of times to open her up before sliding the head in. "Sorry Leanne, I'm fucking for my life here," I offered as an excuse.

"You're fucking for your wife too," Rachael chipped in, "just do what he says so he leaves us alone".

Well I did my best to appear not to enjoy it, but it was a gloriously satisfying doggy fuck with my wife's younger sister. It was probably only my imagination that told me she was enjoying it too. This masked intruder seemed to be taking enough pictures so he was hopefully enjoying it too. I'd like to have said that I performed heroicly under pressure, and made love to Leanne for hours, but in truth it was totally scary having a man with a gun in the same room as me and my family.

I only mananged to pump her for four or five minutes before I shot my load into her pussy and sat back on my haunches. My cock glistening from her wetness and her hole starting to leak my spunk. We were all surprised at the sound of the front door closing as we none of us had noticed the robber had left.

Both girls quickly grabbed up their clothing and I sheepishly stuffed my cock back in my trousers. We all started to talk at once and apologies and explanations, and talk of calling the police all clashed as we tried to make sence of the whole episode.

It was Leanne, pragmatic as ever, who said, "Look, no-one got hurt, he was just some pervert out on some weird kick. Let's just forget this ever happened ok? No-one would believe it anyway and I certainly don't want to tell anyone all what we just went though."

Rachael and I both vigourously agreed, and though I was slightly disappointed in Leanne's tone, I could understand why she put it that way. I secretly hoped she got more of a buzz out of it than she let on, perhaps I would find out when she next came to visit.

Epilogue

The week had passed calmly enough, Leanne had returned home and Rachael and I had done our best to put the incident out of our minds. Well at least that is the pretence I kept up. Secretly I replayed that twenty minutes in my head over and over, and the email that I got that morning only made it worse... or better.. I couldn't quite decide which.

It was from Mike, it was short and sweet. "Hope you enjoyed it - I knew you wouldn't have the guts to do it by yourself so me and my fake gun had to lend a hand :)"

Attached to the mail were all the pictures he took that evening. I certainly wouldn't be lacking in material to lust over for years to come!