The oppressive darkness of the tunnels stretched ahead of Sally. She pulled the hand drawn map from her pack to check and update it. Her grandfather had told her about the tunnel network on his deathbed. Other members of the family were there but disregarded his talk as the feeble minded ramblings of an old man close to death. Sally though, had had her curiosity piqued. Deducing the location, which was mercifully close to home, she had done a few trips during her free time, finding only precious few pieces of evidence that the location was indeed as her grandfather had described.
Under the pretence of attending a sleepover at a friends house she had loaded a large camping backpack with food, water and a sleeping bag and headed to the location. It had been in a woodland, and on her third visit she had found a desteoyed vent in the ground. She had tentatively eased herself down and discovered a network of tunnels and resolved to come back and spend a weekend exploring.
She had spent Friday evening wandering the tunnels, occasionally finding oddments of militaria and further reinforcing her belief that grandfather was right. She slept and then resumed the next morning. Midway through the afternoon, she found it, a heavy steel door. She ran her finger over its surface. It would take hours with specialist equipment to get through. She wouldn't need it though, as she pulled the double sided key from her shorts pocket and slid it into the lock. A grin slid across her face as she turned and heard the heavy internal mechanism clunking into place.
Sally braced against the door and pushed with all her weight and it lethargically swung open. Inside looked like she imagined it would, an abandoned lab coated in decades worth of dust. Grandad had said that it had simply been abandoned at some point in the cold war. Scientists were marched out at gunpoint and not heard from again. The lab was supposed to have been liquidated. Grandad was the last man out and was supposed to hand over the key to an officer that never showed himself.
Eventually, Sally found what she was looking for, a rack of vials containg blue liquid. This was what theu were working on. A super soldier formula. She uncorked the vial and held it up to examine it. According to the notes, it was administered orally, she simply drank it and it would take effect, though what the effect was, she had no clue. Throwing caution to the wind, she poured the unnatural liquid into her mouth and swallowed hard. The taste was harsh and bitter and she could feel it burn all the way down.
Sally continued to explore the lab, picking up notes and anything of interest. She carefully put them into folders and deposited them in her pack. Anything that wouldn't fit was placed in an orderly manner in a corner. Depending on its effects, she could sell this stuff for a fortune, so she wanted as much info about it as possible for future manufacture.
A sharp stabbing pain hit Sally in the gut. Reflexively, she bent double then lowered herself to the ground on all fours. Her breathing was quick and ragged and her eyes fuzzed in and out of focus. Slowly but surely, she could feel the sharp pain fading and being replaced by euphoria. Deep inside she could feel it radiating outwards. Involuntary moans escaped her lips as she rocked back and forth as she built herself to a crescendo.
She could feel her body start to change. Her fingers stretched longer, their nails growing to a point and around an inch long. Her perspective shifted as her arms grew longer and her spine cracked and popped as her body stretched taller. She could feel her face reshape itself as her cheek bones pushed out and her jaw resculpted itself. She could feel her shorts constrict her as her pelvis grew wider before her legs stretched longer. Carefully, Sally stood up and glanced around, she needed to find a mirror.
After a couple of minutes, she found herself in a changing room and staring at a total stranger in a full length mirror. She had grown from 5'3" to god knows what height, at least 6 feet. Her top had risen up to show off a flat stomach and her bottom ribs looked shrunk, as if she had spent her life wearing a corset. Coupled with her wider hips, it gave her an amazing hourglass figure. Too bad she didn't have the ass to match, was the next thought to come to her as she did a quarter turn to her right.
She was still admiring her new body when the sensation began again, though it felt different this time. Instead of deep inside her bones, it was a dull ache, like the day after a hard run. She could feel herself warming up from the inside, like a fire was burning inside. She dropped to one knee as the heat inside reached an unbearable level and continued to increase. Sweat dripped off the tip of her nose but suddenly stopped, replaced by a fog slowly dancing on her skin.
She felt the heat begin to level off, but was immediately replaced by another concern. Her arm ticked and twitched, then other parts of her body began to spasm. They increased in frequency and intensity until they simply locked up. Sally screamed at a volume she didn't think possible. Shortly afterward, it relented. Sally's whole body felt brand new. As she moved around the lab her entire body felt brand new, her muscles "creaked" like they had never been used before.
Walking felt…odd, like she was off balance. She looked down and saw why. Her thighs were slowly expanding along with her bum. She smiled as they stretched and bulged straining against the cuffs of her shorts. She went back to the mirror and looked over her shoulder at her swelling rump and giving it a playful slap before marvelling at the way it flexed and jiggled in her shorts that now looked painted on.
As Sally admired herself, she could feel her nipples tingle. She knew what was coming next and she placed her hands over her breasts. Steadily they ballooned outward, swelling from a B cup to a C, to a D. Then up to an F cup. She drank in the image of herself in the mirror for a long while.
"Time to see what this body can do." She said to herself.