There was no way we could repeat the pleasure of that gangbang every day but Kath and l agreed that Fiona looked ideal material for turning into a complete sub. She had obviously recognised that at her age, this was her last chance to have some serious sex fun and Kath had made it plain to her that she would have to be prepared to allow fellas to use her for their wildest fantasies as there were plenty of more attractive, younger women on the dogging circuit. I explained to Jack how we intended to use Fiona as a piece of fuck meat, he got very excited at the prospect, but l also told him that he would also have to take being treated as a cuck as this would increase the excitement for Fiona. He said that he had read about that sort of set up and the thought of seeing Fiona treated like that gave him a hard-on, and that he liked the idea of us using him as a cuck. We knew we wouldn't be able to keep it up constantly through the week so tried to keep the days as normal as possible. Having said that, l couldn't resist telling Fiona to bend over the kitchen table while l fucked her, she has a very good arse, especially for a woman her age, she carries a few extra pounds but she is not flabby and has a good figure. Her tits sag a bit but they are still full and heavy so a bit of sagging is to be expected. I gave her arse a few hard slaps as l fucked her, her white skin reddening nicely and her reaction told me she was ripe for more. Jack was sat at the table watching me fuck her and playing with himself when Kath came in and got down to suck his cock. When l couldn't hold back any longer l told Fiona to get on her knees as l unloaded my balls into her mouth, then as Jack was about to cum l told Kath to release him and grabbed Fiona by her hair, guiding her to take Jack's cock in her mouth just as he came. Afterwards, l explained to Fiona that my intention was to make her totally submissive and that it would entail a number of punishment sessions similar to the ones she had seen Kath go through on the DVD. Jack was told that he was not allowed any sexual contact with Fiona without my permission and that Kath had a few ideas for him through the week that he might find painful. I explained the system of a "safe word" as it was possible that some sessions would get quite full-on. Both of them appeared excited at the prospect, they had experimented with bondage and spanking years before but only on a mild basis, Jack admitted that he had watched some serious stuff on the Internet and that he liked to imagine Fiona being put through those sort of things. We needed to kit Fiona out with some suitable outfits as she would not fit into Kath's so decided to take a trip to a local sex superstore. Kath showed Fiona her corset that l like her to wear when we go out, it pinches in nicely to give her a good waist and pushes her tits up but leaves her nipples exposed allowing some good tit movement as she walks. I like to see other men looking at her jiggling tits and prominent nipples and with her high heels and shortish skirt she does look like an old tart which attracts a lot of attention. Fiona was told to just wear her shortest skirt with nothing underneath and one of Kath's blouses which was tight over her bra-less tits which again moved about when she walked. Fiona sat in the front passenger seat as l drove and l told her to get her tits out and hitch up her skirt so that lorry drivers could get a good look at her as we passed them. Kath was sat behind her and she had done the same, allowing Jack to play with her tits and finger her cunt. We got quite a few admiring toots from the truckers we passed. The store was very quiet when we got there, just one young lad serving and a couple of single men looking around. I asked for the bondage and clothing section and Kath soon picked out a similar corset to hers, taking Fiona to the changing room to try it on. Kath obviously told her that she would have to show us what it looked like and eventually she emerged, rather self-consciously in just the corset, leaving her tits exposed which were now even larger and giving her arse a good shape. All three other fellas were now taking an interest as l told her to do a bit of a parade, showing herself off. One of the customers commented that she looked good and that she looked ready for fucking. I told him if he had a condom he could help himself and told Fiona to lean against the counter, bend over and open her legs. The assistant handed the fella a condom from a box on the counter saying this sort of thing seemed to be happening more often lately and could she give him a blow job at the same time. I told him that was fine and he soon had his cock buried deep in Fiona's mouth as the other chap started fucking her. Her tits were swinging as he fucked her so l told him to grab them and give them a good mauling. The other customer was stood watching, he had his cock out, wanking, but Kath wasn't about to waste that, going over to him and kneeling to take him in her mouth. This was no marathon session as all three came pretty quickly with both girls getting a good mouthful of spunk. The two customers were a bit sheepish afterwards but the young lad said it was becoming one of the perks of the job as quite a few customers liked to see their women used by strangers. He also told us of a good dogging location fairly close saying that Thursday's were usually the best days, there were usually a lot of trucks there but others turned up as well. I then explained that we were also looking for some punishment equipment as well. He showed us some nipple clamps that we tried out on the girls and also some paddles, whips and belts that both girls had to bend over for us to try out. I gave Fiona some good strokes of each, Jack used them on Kath but l told him he was too gentle so the assistant took over raising some nice stripes on her arse. By now the two customers had been joined by a young couple, she a very pretty, petite blond, who were watching fascinated as we tried out the whips on the girls. It was obviously having an effect on her as she was clinging tight to her partner, stroking the front of his trousers. I asked if she wanted to strip off and join the fun but she shook her head nervously but never taking her eyes off the two naked arses bent over in front of her. The assistant also showed us some large dildos and strap-ons but said we weren't allowed to try them out for obvious reasons. We picked out a couple of the largest ones, the blond quite embarrassed when l told them that both girls would be getting them up their arses later. Once we had made our selections, the assistant gave us a good discount, l asked if anyone else wanted to use the girls before we left, the two original customers asked if they could have blow jobs while the assistant asked if he could fuck Kath up her arse as he'd never done a woman like that, Kath was quick to respond, laying on the counter with her legs in the air exposing her cunt and arsehole so he could get easy access to either, he had his condom on and l told him to stick it up her cunt first to get lubricated then switch to her bum, meanwhile the customer went round the other side and gave her his cock to suck. Fiona was busy sucking the other one. I noticed the couple move away but only so that they could move behind some shelves, then the girl dropped to her knees in front of her partner, obviously wanting a bit of privacy. I heard the unmistakeable sound of Kath having a mild orgasm as both men came and as they pulled out she kissed the lad and thanked him for a great fuck, he seemed pleased with himself. Fiona kept her corset on as both girls dressed, the other couple carried on browsing rather self-consciously, especially as she had a big spunk stain on the front of her t-shirt where she had spilled some. We returned to the car, Jack asked if he could have his cock sucked as he hadn't been able to take a turn at the girls in the shop so Kath obliged as we drove home. As it was a pleasant day we rounded off with a bbq in our secluded garden with the girls just wearing their corsets and later giving Jack and l a show as they both rolled on the lawn eagerly licking and sucking each other's cunts to orgasm. Jack and Fiona both agreed that the last two days had been the most enjoyable sex they had ever had. We all agreed that we would have the next couple of days relatively normal with just the occasional fucking so that the girls were ready for a good dogging session on Thursday. More to follow if you want me to. The girls really appreciate your comments, the dirtier the better.