After our first two times together, Emily and I spent as much as we could together; any alone time we had, we fucked. However, our fun wasn't to last. When Friday rolled around, Emily got an early call from her office, asking if she could come in that day. They were willing to pay her a bonus, so Emily accepted. Before she left, we stole away for a moment to talk.

"Don't worry, I'll be back by tomorrow," Emily said, as we held each other close. 

"I'll miss you," I said, kissing her gently on the lips.

"Well, you can always masturbate to me," giggled Emily. I blushed, the reaction she wanted. She then kissed me, a passionate, slow kiss, our tongues gently dancing around our mouths. After she left, the rest of us decided to go to the beach, as they were calling for rain the following day.

After getting changed into my swim trunks and shirt, I was about to sit and read while I waited for everyone else when Sam came into the living room. She was wearing a red and white striped bikini top that showed off her 34 c boobs and cutoff jeans that clung to her nice ass.

"How do I look?" Sam asked, tilting her head to the side.

"Great," I replied, surprised how hot she looked. For some reason, all week I hadn't looked at Sam as anything other than my cousin. But now though...I shook my head slightly. Emily's not gone that long and I'm already thinking about her sister, I thought to myself. It didn't help when, as she walked into the kitchen, Sam moved almost seductively. 

Once everyone else came up, we headed to the beach. It was somewhat crowded, but we found a good spot near the waterline. After setting everything up, Sam sat and read for a bit before stretching and stood up. 

"I think I'm going to go for a walk," she said. "Anyone care to join me?" She looked at everyone, myself last. "How about it, Tim?"

"Sure," I replied, getting up. For some reason, the way she asked me and the look she gave caused my penis to harden slightly.

"Take as long as you want, we'll be here," said Sam's mom. We both said goodbye and started walking. Eventually we came to an empty stretch of beach that was cut off from the rest of the beaches-and consequently the other beach goers-by a high sand dune. We couldn't even hear anything except the lapping of the waves and cry of seagulls above us. 

"A nice place," I say, looking around. A short distance from where we were standing was a small cave, something I missed when we first got there.

"It is, very quiet, very peaceful," said Sam, looking at me with something I couldn't place.

"Is there...something you wanted to talk about?" I asked. Something in the back of my mind had an idea about what it was, but I held my tongue until Sam said it.

"I know about you and Emily," she said matter-of-factly. She didn't need to say more; I knew she had found out.

"How'd you find out?" I asked.

"Emily's bikini top. She wouldn't just leave it in the kitchen like that, strewn over a chair. Especially with..." A guy in the house, I finished mutely. 

"Have you told anyone?" I asked slightly nervously.

"Of course not, you idiot," she laughed. "I don't want to get the two of you in trouble. Plus..." She smiled mischievously.

"Plus?" I prompted her. Instead of answering verbally, Sam walked slowly towards me, pressed her body against mine and kissed me hard on the lips. Instead of pulling back, I kissed her back, our arms wrapping around one another. I opened my mouth slightly and her tongue worked its way into my mouth, allowing me to suck on it before I slipped my tongue into her mouth. We stood there a good two minutes, just kissing. Finally we broke the kiss and I looked into her eyes. 

"I've wanted to do that for the longest time," smiled Sam. 

"Oh really," I smiled back.

I couldn't believe that I just kissed Sam, the sister of the cousin I was sleeping with. 

"That's not all I wanted," she said, then looked over at the cave. I got the hint; I nodded, wanting to be with her too. With that, she slipped out of my arms, grabbed my hand gently and we walked-quickly-to the cave, a small indentation really where a blanket was laid out over the sand. I looked at Sam quizzically.

"Emily and I found this place a few years ago; its a nice place to...have fun," she said, with a look that sent shivers through me. Sam then turned to me and our lips met again, parting quickly for our tongues. As we kissed, I reached behind Sam and undid her bikini top, while Sam slid off my shirt. We threw both behind the blanket, as we kept kissing; Sam's nipples poked into my chest as her boobs pressed against me. Still kissing, we slowly made our way to the blanket and laid down, I on the bottom and Sam on top. 

"I want you, Tim. I've wanted you for so long."

"I want you too Sam." And with that, we reached down and Sam shimmied out of her shorts and bikini bottom as I did the same with my swim trunks. My erect penis popped out, causing Sam's mouth to open slightly. 

"What a dick," she murmured. Looking at me again, she smiled before kissing me while sliding her pussy onto my penis. We both sighed before we started moving up and down on one another, my penis sliding easily in and out of Sam's wet pussy . We continued to kiss, moaning softly as our pace picked up. Eventually we turned over, so I was on top as we continued to pound each other.

"Cum...cum in me Tim, like you've done to Emily," Sam moaned.

"I'm going...going to cum, Sam," I reply, breathlessly. It took only a few more movements before I shot a load of cum into Sam's pussy, Sam cumming a second later. We stifled our moans of pleasure by kissing and sucking each other's tongues. As we finally came off from our shared orgasms, Sam smiled at me.

"You were great Tim; no wonder Emily likes to fuck you," she said.

"You weren't bad yourself," I teased. She smiled again before gently pushing me off; on top again, Sam kissed me lighly on the lips before slowly kissing down my body to my semi-erect penis. She took it in one hand, kissed the head and en guided it into her mouth. It didn't take long for my penis to become erect again as Sam licked and sucked it. 

"Oh Sam, that's...wonderful," I breath. Not wanting to be left out, Sam swung her body around so her pussy was over my face. I gently kissed her pussy lips before I slid my tongue into her pussy and moved it around. We licked and sucked each other for what seemed like forever, until we both came came again; Sam must have done this before, as she swallowed all my cum. After we both came as much as we could, we maneuvered so we were face to face, and kissed passionately. I could taste my cum on her lips. 

"Was that better than Emily?" Sam asked mischievously.

"Both of you were good, but maybe a little," I answered. Sam smiled, seemly content with that. Suddenly her phone buzzed, giving its text alarm. Sam reached over and, flipping it open, read it.

"Mom just wanted to know if we were on our way back. Emily is going to be back in a few hours, so they're going home to get ready." Sam smiled at me; we could spend a few minutes, I thought. After a short time, Sam and I got dressed and walked hand in hand back to the beach house. The whole time I was thinking that I was having the greatest summer ever. Little did I know it was going to get better.

To be continued...