Years after my initial voyeur experience I had another thrilling opportunity that led to a very fun time. This experience started out rather innocently but has grown to be the highlight to my summer vacation each year and gives me great excitement just thinking about its impending arrival every summer. Every summer we rent a cottage up north on a nice lake, and share the rental with my wife's sister and her family. We have been doing this for about 4 years now and its always a great time. My sister -in-law is a nice girl and she and her husband always provide good companionship and fun for all of us. She is a year older than my wife and quite attractive considering she is close approaching 50. Her husband is a pleasant fellow but was a bit of a player when he was younger and I suspect still steps out fairly regularly. He doesn't really spend much time with his wife and I think their love life suffers because of it. The first year we rented this cottage, we rent the same one every year, I noticed that the room my wife and I share had a window that looked out on to the side deck and if we were not careful to close the blinds someone could look straight into the room from the chairs on the deck. I thought nothing of this at the time, as this area of the deck was seldom used because it was in the shade, and we continued on with our good times. Now because it was vacation and the alcohol was flowing each evening, I was always a little slow to rise from bed in the mornings. Everyone else tended to get up early and mill about in the kitchen and out on the front deck in the morning sun. I was laying in bed one morning about 2 days into the stay when I heard a scrape of a chair just outside my window. I rolled over on my elbows and peeked out the window to see my Sis-in-law sitting in one of the chairs having her morning smoke. This was kind of exciting. If the blinds on my window were open she would be able to look right in the window from where she sat and have a full length view of my bed. The rise of the deck would allow her a completely unobstructed view of me laying in bed. This thought excited me greatly and started an evil spark in my mind that had to be satiated. I decided that this opportunity could not go wanting, but it had to be accomplished with incredible subtlety or I could find myself in divorce court. I needed to make sure that I had complete deniability and that my plan went off in such a way, that it would appear to be a total accident. If what I was going to do wasn't well received by the intended viewer it could be simple explained away. So the planning began. I had to watch her pattern and also wait for my window of opportunity to open. Couple of more days went by and the week was nearing its end and I was getting worried that I wasn't going to be able to accomplish by plan. Then on the morning of the 6th day I saw my chance. The night before we had partied pretty hard and I was lagging in bed again, as usual. My bro-in-law had gotten up early and gone fishing and my wife was awoken by him leaving, so she headed down to the lake for a swim and some sunning. I heard Melissa, my sis-in-law stirring in the kitchen making her coffee and knew she would be heading out on the deck in a few minutes for her smoke. I quickly jumped into action with my plan. I fiddled with the horizontal blinds at the bottom of the window on one side. So it appeared that they had been caught up on the curtains. This allowed someone to see in through the slot clearly but still looked as if the blinds were closed and the person in the room, Me, was unaware that they were visible. I of course was very aware! I then shucked off my boxers and because I was hung over and it was morning and I was absolutely terrified and excited, my cock was standing straight up at attention and throbbing with excitement. Then I laid back down in bed and covered myself with just the sheet. I laid on my back to afford a full view of my erection standing up straight and proud and I put a pillow over my head so I could look back at the window yet still appear to be sleeping. Then I waited for Mel to appear on the deck with her coffee. Now, I have to say that this few minutes were some of the most exciting and terrifying of my life. A shadow appeared on the window and I heard her move the chair into her normal spot. I listened for other voices, but heard none. This was it. I waited and squinted from under the pillow to see if she turned towards the window. Nothing. She appeared to be looking out towards the lake. This would suck if she never looked in the window. I waited my hard cock still creating a nice tent with the bed sheet. It would look very normal. Just a hungover guy with some morning wood. Finally she moved and I could see now from my spot under the pillow that she had noticed the gap in the blinds. I watched as she looked around to see if anyone was near. Then she moved her chair slightly to the side and now she was in a place she could stare straight in the window without turning her head. My god! not only was she watching but she seemed interested at the idea. My balls ached! I stayed that way for a few minutes, I moving my legs every once in while to move the sheet around my hard cock and then I decided it was time to go for it. I pretended to start to wake and I stretched and slid my hand under the sheet to feel my morning cock. I rubbed myself slowly. It had to be slowly, with the level of excitement I was at I was afraid I might cum at any second. I then slowly slid the sheet off of my proud erection and began to masturbate myself. Melissa was less than 5 feet away from me and from where she sat she would have a perfect view my very hard cock and me stroking myself to climax. As I said earlier the level of excitement served to bring me to ejaculation very quickly and the volumn of cum was incredible. I laid in bed for a few minutes stroking my slick cock covered in my juice and I soon began to harden again. The situation was exhilarating and I rubbed my cock that way for almost ten minutes. The whole time this was going on Melissa sat still on her chair and never moved or looked away. Her eyes were fixed on my hand and my eyes, from beneath the pillow, were fixed on her. After about ten minutes I heard voices returning and I decided it was time to beat a hasty retreat. Melissa also quickly got up from her chair and headed back around to the front of the cottage. I cleaned up and threw my swim trunks on and went out to the kitchen for a coffee. As I stood making my morning java Mel came in from the deck and smiled as she passed me. I just played it cool and went about my business, all the time thinking that this was not going to be the last time I tried this. You might think this was the end of the story........well it was for that summer but when we returned the following year I got a bit of a surprise!