Chapter 1: In the beginning

As a teenager Frank Marsden was more unruly than most teenagers. He had been caught several times, by his father when he was interfering with their farm animals.

Warnings didn't upset young Frank, he just became more secretive and careful.

During those years he became more obsessed with animals and especially with animal/human relationships.

Frank had no formal training as a veterinarian, he gained skills by watching animals mating and experimenting.

He was 25 when he first met 17 year old Nancy McNamarra and within weeks of meeting her they had a sexual interlude in the barn. Nancy followed Frank into the barn one afternoon, to her it all seemed quite innocent. What Nancy didn't know was that Frank had planned it. When he saw her Frank just grinned at her. Nancy quickly realised because of his age, Frank was quite experienced at this sort of thing. She also realised that her age wasn't going to bother him.

It all seemed so natural, for Nancy standing in front of Frank, wondering what his next move would be. Seconds later, Nancy found out. Frank reached out and spun her around causing her to lose her balance and as she did she found herself laying face down on something soft and comfortable with her skirt up around her waist and her panties on the floor. She looked back and there was Frank, completely naked. Her eyes opened wide as she saw his thick cock poking straight out from his crotch.

Moving forward between her legs, he lowered himself onto her, covering her as a stallion covers a mare.

He pushed the head of his throbbing cock hard against her now wet opening and started pushing it between the spreading lips. Nancy clamped her teeth tightly way up into her, with tenderness. It was a thrilling experience, her first time with someone she thought to be a real man.

She was aware of every inch of Frank's manhood moving into her, stuffing her cunt and stretching it to accommodate his thick member. She gasped with delight as he buried his huge cock deeper into her. She felt the throbbing head of his cock pushing against her cervix while his huge balls were brushing against her pussy lips.

She was gasping for breath as he pumped his cock in and out of her, moments later she was swept into an orgasm and she heard Frank groaning as he sent his hot load of come deep into her cunt. She lay there panting and gasping, as Frank laboured over her. Then suddenly they weren't fucking, but it was anything but over. Frank just lay on top of her with his cock firmly embedded inside her.

Suddenly he pulled his cock out of her, rolled her over and shoved his cock back into her again. She was clinging to him as he began moving back and forth inside her again. She flung her legs up over him, as he drove his cock all the way into her as he climaxed again.

Visits to the barn became a daily ritual, some days more than once. Nancy had never bothered to take any precautions against pregnancy and Frank hated condoms. Three weeks after her eighteenth birthday, Nancy informed Frank that he had gotten her pregnant.

Frank and Nancy married a month later and just over eight months later their daughter, Maureen was born. Then fifteen months later, twins, Robert and Melanie were born.

The Marsden's married life was uneventful for the next sixteen years. Frank's sexual drive waned over those years. Nancy was still a beautiful woman at the age of thirty-six. Her sex life wasn't what she wanted it to be, she was always sexually frustrated.

Frank decided to sell the small farm they had lived on for all of their married life. He purchased a larger property. The homestead had a well equipped laboratory. It was Robert who discovered the bottles of tablets and liquids. None were labelled. Neither