It only took an instant for Rachel to realize that the stag could smell her and Zoey, and then further realize that Zoey was already standing closer to him.
Rachel wasn't thinking about the prize money; as horny as she was, she was still too freaked out by this entire transformation process, and her normal instinct took over long enough for her to turn and run.
The stag immediately saw and heard her, and bounded down the hillside, not realizing Zoey was there also, and nearly landed on her.
Zoey took a step to turn and run, and immediately tripped and fell to her knees. The stag looked down at her round, bare posterior, and that was all it took.
Rachel had run maybe a thirty or forty yards when she heard Zoey shriek, then groan, then deeply moan. Rachel ducked behind a tree and looked back.
She saw a beautiful, naked woman (Zoey) on all fours, her breasts dangling and rocking beneath her, being rammed by a stag from behind. Despite the violence of the buck's thrusts, Zoey's groans were clearly of pleasure, and her eyes were rolling up into her head. With each thrust, the stag let out a bleat or bellow, which had a passing trace of a human-like voice to it. And with each thrust Zoey became less and less human.
First her boobs began to flatten. Then the tip of her nose darkened. The her hair on her head shortened and turned tan, and started to creep down her neck. Then her eyes changed shape and darkened. Then her butt lifted and her back straightened. Her arms lengthened. Her legs cracked and changed shape. A tail sprouted at the top of her ass. Her toes receded until she only had two on each foot. Then the same happened to her fingers. Her face pushed out more into a snout. Her fur spread from her head down her back, over her pubes, then her whole body. Her four legs finally narrowed and grew into hooves. Her neck lengthend. Only her voice remained that of a human female as she entered into the moans of the longest orgasm Rachel had ever heard.
Far from being horrified, as she felt at first, Rachel was soon watching the stag fuck Zoey through her transformation with rapt interest. She had two fingers on both sides of her clit, stroking to match their every thrust, while she twisted her nipples with her other hand. She was soon full-on finger fucking herself, more vigorously than she ever had. She closed her eyes as Zoey came, and focused on driving herself over the edge, but didn't seem able quite to get there.
As Rachel started to become slightly frustrated, her hand inside her dripping snatch, legs spread, balanced against the tree, she opened her eyes to see the doe which had been Zoey walking up to her. The stag was only a dozen or so paces behind.