Sarah Thompson stared at her reflection in the bathroom mirror, tracing the faint scar above her left eyebrow with her fingertip. It had been there as long as she could remember, a thin white line against her pale skin, a remnant of some childhood mishap she couldn’t quite recall. Her husband, David, always said it made her look fierce, like a warrior queen. She smiled weakly at the thought, but lately, that reflection felt like a stranger’s.

It started three months ago with the headaches. Sharp, stabbing pains that came without warning, leaving her doubled over the kitchen sink or slumped against the steering wheel in the grocery store parking lot. David fussed over her, booking doctor’s appointments, urging her to rest. The neurologist ordered scans, but everything came back normal. ‘Stress,’ the doctor said. ‘You’re a high-strung perfectionist, Sarah. Try yoga.’

But the dreams were worse. Night after night, she wandered through unfamiliar rooms—a cramped apartment with peeling wallpaper, the scent of cheap jasmine perfume hanging in the air. In these dreams, she wasn’t Sarah Thompson, graphic designer, wife of ten years. She was someone else, pleading with a shadowy figure, her voice raw and desperate. ‘Please, David, don’t leave me.’ She’d wake up sweating, David’s arm heavy across her waist, his steady breathing a anchor to reality.

One Saturday morning, while David was at his adjunct professor job at the community college, Sarah decided to tackle the basement. Clutter had accumulated there since they bought the house fifteen years ago, boxes of forgotten relics from their early marriage. She hauled down trash bags, determined to reclaim the space. In the far corner, behind stacks of holiday decorations, she found a small metal lockbox, rusted at the edges. No key, but the latch popped open with a crowbar.

Inside were yellowed envelopes, a few faded photographs, and a plastic laminated card. Sarah’s breath caught. The card was a driver’s license from another state, expired in 2009. The photo showed a woman who could have been her twin: same heart-shaped face, same hazel eyes, same scar. But the name read ‘Lydia Grant.’ Birthdate: one day before her own. Height, weight, all matching.

Her hands trembled as she rifled through the envelopes. Letters in looping handwriting, addressed to David. ‘My love, I can’t live without you. Sarah doesn’t deserve you.’ Sarah’s stomach churned. Sarah? That was her name. She grabbed her phone and snapped photos, then shoved everything back and fled upstairs, heart pounding.

David came home to find her curled on the couch, the lockbox open on the coffee table. ‘What’s this?’ he asked, his voice casual, but his eyes darted nervously.

‘I found it in the basement. Who is Lydia Grant? And why does she look exactly like me?’

He sat beside her, rubbing his temples. ‘It was a Halloween party, babe. Fifteen years ago. I dressed as a professor—you know, tweed jacket—and you went as this missing woman from the news. Lydia Grant. She vanished right before we met. You thought it was funny, ironic. The ID was fake, part of the costume.’

Sarah searched his face. ‘Why hide it?’

‘You were superstitious back then. Said it brought bad luck. We boxed it up and forgot.’ He kissed her forehead. ‘It’s nothing. Let it go.’

But she couldn’t. That night, as David slept, she googled ‘Lydia Grant missing.’ Articles popped up from 2009: 32-year-old artist, last seen arguing with boyfriend in a bar. No arrests, case cold. Photos confirmed the doppelganger. Commenters speculated murder, body dumped in the river. Sarah’s scar itched.

The next day, she called in sick and dove deeper. Social media archives showed Lydia’s profile: vibrant, posts about painting, tagged with a David in some photos—not her David, but the build was similar. No, it was him, younger, smiling awkwardly. Tagged as ‘David Ellis,’ adjunct professor.

Panic rising, Sarah drove to the old apartment complex Lydia last lived in, an hour away. The super remembered her. ‘Lydia? Yeah, sweet girl. Had a roommate named Sarah, best friends. They fought a lot over some guy. Lydia disappeared after Sarah’s car accident. Cops questioned Sarah, but she had an alibi.’

Sarah’s world tilted. Roommate named Sarah? She probed gently. ‘What did Sarah look like?’

‘Tall, blonde like you? Nah, Sarah was brunette, no scar. Lydia had the scar.’ He scratched his head. ‘Weird case.’

Driving home, Sarah’s headache exploded. Flashes: blood on dashboard, Lydia’s face twisted in anger. ‘You stole him from me!’ No, that couldn’t be her memory.

She confronted David that evening. ‘You dated Lydia Grant. She vanished after you left her for… me?’

David sighed, defeated. ‘Okay, truth. Lydia was unstable. Obsessed. We dated briefly before you and I met. She stalked us, threatened to kill herself—or worse. One night, she cornered you in your apartment, high on pills. You fought, she fell, hit her head. It was self-defense. We panicked, hid the body, you took her ID as a reminder. But she was declared dead years ago. It’s over.’

Sarah recoiled. ‘I killed her?’

‘No! Accident. We protected each other.’ He held her. ‘You’re my Sarah.’

Doubts gnawed. Friends acted strange when she mentioned Lydia—averting eyes, changing subjects. Her best friend, Mia, finally cracked over coffee: ‘You were devastated back then. Lydia was your roommate, stole your designs, slept with David before you dated him. When she disappeared, you blossomed.’

Sarah’s memories fractured further. She ordered a DNA test from an ancestry site, using Lydia’s name. Waiting for results, she scoured the house. In David’s study, behind diplomas, a hidden drawer: love letters from Lydia to David, passionate, unhinged. And a photo: David with two women—Lydia and a brunette Sarah, unmarked face.

The brunette. That was supposed to be her? But she had the scar.

Results arrived via email at midnight. Sarah clicked, heart hammering. Match: 100% to Lydia Grant family tree. No hits on Sarah Thompson lineage.

David found her sobbing at the computer. ‘What is it?’

She thrust the screen at him. ‘I’m not Sarah. I’m Lydia.’

He knelt, eyes soft. ‘You’ve always been my Sarah, Lyds. That night, fifteen years ago—you drove drunk to confront your roommate Sarah after she stole me from you. You crashed, killed her instantly. Her body mangled, unrecognizable. You saw your chance: same build, you altered records, scarred your face to match the crash story, took her life. I loved you first, helped bury it all. We’ve been happy.’

The room spun. Flashes aligned: the crash was her rage. The scar from smashing mirror in guilt. Dreams were resurfacing truths. David’s ‘protection’ was complicity.

‘Why tell me now?’ she whispered.

‘Because your guilt is eating you. The headaches—it’s time to face it. We can move, start fresh as us.’

But as he embraced her, Sarah—no, Lydia—saw the lie in his eyes. He’d waited for her to crack, to take the fall alone. She pushed away, grabbing the letter opener. ‘You never loved me. You loved Sarah.’

David’s face hardened. ‘Prove it.’

She lunged, but he was faster, hand clamping her wrist. They struggled, crashing to the floor. In the chaos, her head struck the table edge—same scar blooming anew. Darkness swallowed her.

When she woke in the hospital, David smiled down. ‘Sarah, you had a fall. Everything’s fine.’

The mirror showed the familiar face. But now she knew: the woman she wasn’t had died long ago, and the killer lived on, trapped in stolen skin.