Someone Kept Leaving Threatening Notes in My Apartment Where I Lived Alone — When I Found Out Who, I Was Shaken to My Core

It started on a Tuesday morning, though lately, all my mornings had begun to blur together in a hazy fog of too little sleep and too much coffee. I was making breakfast, or trying to.

The toast was already in the toaster when I opened the fridge for eggs and saw it: a yellow Post-it note stuck right at eye level.

“Get groceries. Running low,” it read in messy handwriting that definitely wasn’t mine. I always write in neat print, a holdover from my teaching days when I had to ensure thirty second-graders could read my instructions.

I traced the jagged letters with my fingertip, frowning.

The ink seemed fresh, slightly smeared at the edges, as if someone had written it recently. The thought sent an involuntary shiver down my spine.

“That’s weird,” I muttered, reaching past the note for the eggs. “I don’t remember writing that.” The carton felt unusually light — only two eggs left. Had I used that many?

The acrid smell of burning toast snapped me out of my confused staring.

I yanked the blackened bread from the toaster, waving away the smoke that curled toward my ceiling in lazy, accusatory spirals.

My ancient ventilation system wheezed pathetically, doing nothing to clear the air. The fan sounded like an asthmatic cat, which would have been funny if it wasn’t so annoying.

“Great. That smell’s gonna be here till tonight.” I tossed the ruined toast in the trash, my appetite gone. “Add that to the list of things wrong with this place, right after the temperamental heating and the mysterious water stains on the bathroom ceiling.”

I probably would have forgotten about the note entirely if things hadn’t started getting weird. Really weird.

Two days later, I found my keys in the fridge and another note stuck to my laptop, “Project report due Friday. Don’t mess up this time.”

The words made my stomach clench. I’d been struggling with focus lately, sure, but the tone felt so… judgmental. Like someone was watching me, cataloging my mistakes.

That same day, I discovered a bottle of orange juice in my microwave. I never buy orange juice — it’s too acidic for my stomach. The seal wasn’t even broken. The orange liquid seemed to glow eerily through the microwave window like some kind of warning.

I picked up my phone to call… someone. The police? My sister?

But what would I say? “Help, someone’s breaking into my apartment to remind me about work deadlines and buy me breakfast drinks”?

I set the phone down, rubbing my temples where another headache was blooming.

“This is insane,” I muttered. I took a deep breath and instantly regretted it as the stale air in my apartment hit my lungs. “I need to get more air freshener.”

The thought slipped away as quickly as it came, lost in the fog that seemed to be filling my brain lately. Didn’t I already buy air freshener this week? I vaguely remembered standing in the grocery store aisle, staring at the shelves, but had I actually purchased anything?

The next morning, there was a new note on my bathroom mirror: “Be grateful for all the reminders, it’s tough to keep track.”

The message was written in red ink this time, the color vivid against the steamy mirror. I wiped my hand across the glass, but the condensation just made the ink run, turning the words into crimson teardrops that slid down the mirror’s surface.

I stared at my reflection, at the dark circles under my eyes that seemed to be getting worse. My normally bright green eyes looked dull, and my skin had taken on an unhealthy pallor.

A stranger stared back at me, someone I barely recognized. “What the hell is going on?”

The question hung in the air, unanswered. But somewhere in the back of my mind, a voice whispered that I might not want to know the truth.

That’s when I decided to set up the webcam. It wasn’t anything fancy, just a basic security camera aimed at my desk.

I figured whoever was getting into my apartment had to show up on camera eventually. I’d been watching enough true crime shows lately to know you needed evidence before going to the police. Otherwise, they’d just dismiss you as paranoid or attention-seeking.

My sister always teased me about my true crime obsession. “One day you’ll start seeing suspects everywhere,” she’d joked last month.

Now her words felt less like teasing and more like prophecy.

I spent that evening testing different angles, making sure the camera could capture most of my living room. The LED display blinked steadily, its red eye watching over my space like a mechanical guardian.

Every creak of the building made me jump, every shadow seemed to hide a potential intruder. The ice maker’s sudden clunk made me nearly leap out of my skin.

When I finally went to bed, I left every light on in the apartment, trying to ignore how the utility bill would suffer.

“You’re being ridiculous,” I told myself, pulling the covers up to my chin. “Nobody’s breaking in just to leave you notes about grocery shopping.”

But even as I said it, my eyes kept darting to the bedroom doorway, searching the shadows for movement.

My dreams that night were strange, fragmented things. I kept seeing someone moving through my apartment, a familiar silhouette that never quite came into focus.

But every time I tried to concentrate on their face, it would blur and shift, like trying to see through foggy glass. I woke up with my heart racing and another crushing headache, my sheets damp with sweat.

The morning light should have been reassuring, but instead it just illuminated my growing paranoia.

The camera was gone. Just… gone, like it had never existed.

And there was a new note on my fridge, the yellow paper almost glowing against the white surface: “Milk! You’re really slipping. How many times do I have to remind you?”

The handwriting seemed angrier somehow, the letters pressed so deep into the paper they’d nearly torn through.

I touched the indentations with trembling fingers, trying to remember if I’d written it myself. The pen marks had that same fresh quality as the first note, slightly smudged as if the ink hadn’t fully dried.

Had I gotten up in the night? Everything felt so fuzzy lately, like trying to remember a conversation underwater.

My neighbor’s newspaper thudded against the hallway floor, the sound impossibly loud in the morning quiet. I pressed a hand to my chest, feeling my heart race beneath my palm.

This was getting ridiculous. I needed fresh air, needed to get out of this stuffy, cramped apartment that suddenly felt more like a trap than a home.

I practically ran out of my apartment, not even bothering to check my reflection in the mirror (I knew I looked as terrible as I felt.)

That’s when I bumped into Ron, quite literally colliding with his solid frame in the hallway.

“Melanie?” He caught my elbow to steady me, his forehead creased with concern. His hand felt warm, real, anchoring me to the moment. “Are you okay? I’ve been worried since you came by last night.”

I froze, my blood turning to ice water in my veins. “What?”

“Last night,” he repeated slowly, his grip on my elbow loosening but not letting go entirely. His brown eyes searched my face, and I wondered what he saw there. “When you stopped by?”

“I didn’t come by last night,” I cut him off, my voice sharp with fear. “I was home all evening.”

Ron’s brown eyes widened, and something flickered across his face — concern? Guilt?

“But you did. You seemed really distracted and weird though. I’m not sure why you insisted on giving me that thing and I want to return—”

“I’m late for work,” I blurted, practically running to my car.

The hallway suddenly felt too narrow, too close, like the walls were pressing in. As I fumbled with my keys, dropping them twice before managing to grip them properly, a memory surfaced: Ron’s spare key to my apartment, the one I’d given him months ago to feed my fish while I was on vacation.

He’d said he lost it, but had he? The implications made my head spin. Trust, safety, sanity — how many things could you lose before you noticed they were gone?

I sat in my car, trying to steady my breathing. Ron had been the perfect neighbor since I moved in two years ago. He was quiet, considerate, and honestly kind of cute.

We’d developed a comfortable friendship, sharing takeout when we both worked late and watching each other’s places during vacations.

I’d even caught myself daydreaming about asking him out for coffee, or dinner — something more than our casual hallway chats.

But now? Now I couldn’t stop thinking about that key, and how he always seemed to know when I was having a bad day. About how he could probably hear everything that happened in my apartment through our shared wall.

At work, I couldn’t focus. My headache was getting worse, and the fluorescent lights seemed to drill into my skull.

My coworker, Sarah, kept shooting me concerned looks.

“Mel, you look terrible,” she finally said during lunch. “Maybe you should go home.”

I shook my head, immediately regretting the movement. “Can’t. Got that project due Friday.”

“That was last week,” Sarah said slowly. “You turned it in already. Remember? Jenkins even complimented you on it.”

I stared at her, my half-eaten sandwich forgotten. “But… the note said…”

“What note?”

How could I explain that someone, maybe my seemingly perfect neighbor, was breaking into my apartment to leave me passive-aggressive reminders? That I was losing time, finding things in strange places, and couldn’t trust my memory anymore?

Two days later, I found the note that broke me: “We should talk soon, before it’s too late.”

It was stuck to my bedroom mirror, which meant someone had been in my room while I slept. The thought made me physically ill.

Something in me snapped. I marched straight to Ron’s apartment, ready to demand answers. When he opened the door, the first thing I saw was my missing webcam on his shelf.

“You!” I jabbed a finger at his chest. “You’ve been sneaking into my apartment! You took my webcam!”

“What? Melanie, no! You gave that to me, remember? When you came by? I tried to give it back to you the other day but you—”

“Stop lying!” The room started to spin. Black spots danced at the edges of my vision. “I never… I didn’t…”

The last thing I remember was Ron’s face swimming above me as everything went black.

I woke up in a hospital room with an oxygen mask strapped to my face. The steady beep of monitors replaced the usual hum of my ancient AC unit. Ron was there, looking worried, and so was a doctor with kind eyes and silver hair.

When I reached up to remove the oxygen mask, the doctor put out a hand to stop me.

“That has to stay on, miss,” the doctor said. “When your friend brought you in here, your bloodwork showed high levels of carbon dioxide. Tell me, have you experienced any of the following symptoms lately: headaches, confusion, memory lapses, possibly even hallucinations?”

I stared at the doctor in shock and nodded. It took a moment to find my voice, but when I did, I told him about the notes, the misplaced items, and everything else that had been going on the past few days.

“The symptoms you describe and the lab results from your blood tests suggest you’ve been suffering from carbon dioxide poisoning.”

“The ventilation system,” Ron added softly. “I kept telling the landlord it needed to be checked, especially in these old buildings.”

“What? But… carbon dioxide poisoning? I didn’t even know that was a thing. And what about the notes?” My voice sounded small. “Why would I threaten myself?”

The doctor’s smile was gentle. “The mind does strange things when it’s oxygen-deprived. Especially if you’ve been watching a lot of true crime shows lately.”

“How did you know I was watching true crime shows?” I asked the doctor.

“You mentioned it several times while we were waiting for the ambulance,” Ron said.

“Right before you passed out, you were convinced I was recreating episodes of some show about neighbors stalking people.”

My face burned with embarrassment. “Oh, God.”

“I suggest you get a carbon dioxide detector for your home,” the doctor said. “Standard smoke alarms won’t pick up high levels of CO2. You got off pretty lucky this time, but you’ll have to follow up with your regular doctor to check if you need ongoing oxygen therapy.”

After I was discharged, Ron insisted on coming with me to buy a CO2 detector. When we plugged it in at my apartment, it immediately started screaming.

“I’m so sorry,” I said, watching him disable the alarm. “I accused you of — God, I made such a fool of myself.”

“Hey.” Ron’s voice was warm. “Anyone would have been scared. Though maybe ease up on the true crime for a while?”

I laughed, the sound shaky but real.

“Yeah, I think I’ve had enough mystery in my life lately. But I still don’t understand… was I really writing those notes?”

“According to Mrs. Chen across the hall, she saw you putting notes on your door several times last week, and taking them down again. You seemed really focused, she said, like you were on a mission.”

“And the webcam?”

“You brought it over, insisting I needed to check my apartment for notes and moving items. You were really worried about me.” His lips twitched. “It was kind of sweet, in a delirious sort of way.”

As we worked to air out my apartment, Ron stuck something to my fridge. It was a Post-it note, but this time the message made me smile: “Take care of yourself.”

Looking at his neat handwriting — so different from my messy scrawl when I was CO2-addled — I thought maybe some mysteries have happy endings after all.

“Hey Ron?” I called as he was leaving. “Once my apartment isn’t trying to kill me anymore… maybe we could get coffee?”

His smile lit up his whole face. “I’d like that.”

Here’s another story: Trent’s world unravels when he finds a cryptic note in his nine-year-old daughter’s backpack: “I’m your real dad, come and see me.” Suspicion gnaws at him, but nothing prepares him for the shocking truth he uncovers. Click here to keep reading.