Twisted Transformation in a Late-Night Pharmacy

A girl enters a small late-night medical drug store holding a prescription, tired and slightly anxious; realistic Korean horror, narrow aisles filled with medicine boxes, glass cabinets, cold fluorescent lighting, quiet empty atmosphere.
She approaches the counter and asks the pharmacist for her medicine while he searches the shelves.
Her fingers freeze around the prescription; repeated scanner beeps echo through the silent store as the fluorescent lights begin flickering.
She suddenly stares toward the medicine aisle, sensing something behind her.
Her fingers begin twitching uncontrollably, slowly curling into unnatural positions.
She violently convulses against the counter; the pharmacist stumbles backward as medicine bottles fall from the shelves.
She collapses behind the counter, one arm twitching at an unnatural angle, her limbs becoming rigid and distorted.
She slowly rises again with wide unfocused eyes, a slack face, bent joints, and unnaturally twisted limbs.
Her head tilts at a broken angle as she stares directly at the pharmacist without blinking.
The pharmacist backs away in terror as her arms suddenly bend backward at the elbows.
Her jaw stretches impossibly wide, revealing an unnatural scream that echoes through the pharmacy.
She suddenly lunges forward over the counter with explosive speed, forcing the pharmacist to run.
She vaults over the counter with backward-bending limbs, moving unnaturally fast between the narrow aisles.
She stands completely still between the medicine shelves, wide unfocused eyes staring toward the entrance.
A customer enters and freezes when she slowly turns her head toward them.
Her fingers twitch as her bent joints and distorted limbs begin moving again.
She suddenly lunges down the aisle, knocking medicine boxes and bottles from the shelves.
The customer runs toward the exit and trips over a fallen basket.
The pharmacist grabs a fire extinguisher and pulls the pin with shaking hands.
White powder blasts into her face; she recoils into a glass medicine cabinet, her limbs folding at unnatural angles.
She slowly rises from the cloud, powder covering her face, wide unfocused eyes locked on the pharmacist.
Her jaw drops and stretches impossibly wide again as she suddenly lunges toward him.
He sprays the extinguisher continuously while backing toward the entrance.
She crashes through the glass door, her bent limbs twisting unnaturally as shards scatter across the empty nighttime street.
The pharmacist and customer stare through the shattered doorway in silence.
Final CCTV angle from inside the medical store; empty aisles, flickering lights, scattered medicine boxes.
A single medicine box slowly falls from a shelf. Cut to black.