This story goes back to when I was married to my first wife Jane, and I was a mere twenty four. My mother-in-law Sarah was fifty three but is good shape, and liked to dress well. As her husband worked abroad, Sarah was on her own for months at a time, so I became the occasional 'fix it' man. When my wife and I visited her, there was normally a list of things for me to do. Anyway one time the list was longer than I could fix in the time we were there, so I planned to return the next week. I happened to call the day she was going out with a friend that evening and when she answered the door, she was in a black dress so I commented that she looked great in it. Previously I discovered my mother-in-law often wore stockings and suspenders, and this always gave me a hard-on. She also knew my wife did not like to wear them, so this may have been the reason she gave me a glimpse 'accidentally on purpose' quite often, probably knowing the effect it had on me. This happened many times and this was in my mind when she answered the door. She was obviously still getting ready as she had a lipstick in her hand. When she turned round, I saw the zip on the dress was still down and the dress was open enough to see the black bra strap but not open so low as to see her knickers. Anyway she disappeared and I started to fix the problem I had planned to. As I did she called me and as me to zip her up. I was in like a flash! When I pulled at the zip the dress pulled away from her back and I could see not only her black knickers, but a black suspender belt. It was like a bloody lighting bolt and I stood to attention, but gasped slightly at the same time. She heard me and asked what is wrong. I just had to spill the beans and say you're all dressed in black and with stockings! With that she turned to me put her arms behind her back and pull the zip down again. I though it was a problem but she then pull the dress off her shoulders and let it fall to the floor. I thought my cock was going to burst as she looked great. She asked then if she still looked good. All I could say was "wicked". My hard on was obvious this. With that I took her bra straps off her shoulders and pulled them down further to take her bra off her breasts. No objection so I started to suck her nipples. I was like turning the light on. She went for my cock, and I felt her pussy through her knickers. Damp and getting wetter as she pulled out my cock and started to wank me. I stopped her, bent down and pulled her knickers off. That was it! I stood up turned her round, bent her over and slipped my cock into her fully. Thankfully she came within a minuted and gripped my cock tight with her pussy. I kept going but the sight of her in stockings and suspenders, was building the pressure in my balls. I slipped out of her rubbed her ass with the tip of my cock and she push a little to let me know she was good to go. In I went, and 30 seconds later filled her with my sperm. As I pulled out there was not a drop left in me! I held her breasts and enjoyed the end of my orgasm thinking about what we had just done, and the door entry buzzer rang. Her friend. A rushed tidy up and she was at the door saying hello, with me still reeling! When I got home my wife as if all was well. Too right it was. After that I was on call to fix things and I have more to tell on the extra events that we go up. What a sneaky mother-in-law!