The battery on my front door smart lock died, so I called a locksmith to come over.

While he was working on the lock, he made small talk. "Dude, this lock comes with six spare keys. Did you lock all of them inside the apartment?"

I froze.

I've lived in this apartment for three years. My wife and I each have one spare key. The other three were always kept in the hallway drawer.

That makes five total.

So where's the sixth key?

I watched the locksmith work and asked him, "Are you sure there are six?"

"Positive. This German lock cylinder comes standard with two master keys and four secondary keys. A lot of families have them installed. I wouldn't get it wrong."

He glanced back at me. "Sounds like you might be missing a key. You'll want to track that down. If you're sure it's lost, get the lock changed. Last thing you need is some thief finding it."

I didn't say anything, but I was confused. I only remembered five keys in total. I'd never seen a sixth one.

The only reason I'd called a locksmith in the first place was because I'd left my keys at the office and needed to grab some documents in a hurry.

Just then, I heard a click, and the door opened.

I Venmoed the locksmith fifty bucks, walked inside, and opened the drawer at the back of the entryway.

Since we usually used the fingerprint scanner and keypad, the three spare keys—each with a little cartoon charm—were still lying in their velvet box. Add the two keys that me and my wife, Jessica Carrington, were carrying, and that made exactly five.

Jessica always handled things around the house.

I was starting to worry that the locksmith might be right and we'd actually lost a key. I was about to text Jessica when my phone screen lit up. It was an alert from my front door security camera, saying someone had been loitering suspiciously.

I tapped on the playback.

The footage showed that half an hour earlier, a tall, thin man had carefully avoided the camera's main angle and stood sideways in front of my door. He pulled a key out of his pocket and inserted it into the lock as naturally as if he were walking into his own home.

Just as he stepped inside, his side profile turned directly toward the camera.

That face — I would never mistake it.

It was Jessica's ex-boyfriend, Kyle Summerton.

Three years ago, their breakup had caused a huge scene. Jessica had even blocked him everywhere just to get away from him.

And now, this guy who'd disappeared for three years had one of my house's spare keys in his hand.

But that wasn't even the point.

I frowned and slowly dragged the video forward.

Then I realized with horror that Kyle had walked into my house half an hour ago — and never walked back out.

A chill ran down my spine. I scanned the room.

Just as I was about to head for the bedroom, I heard the fingerprint unlock sound from the front door.

Jessica walked in, full of energy.

She saw the spare keys in my hand and said in a slightly scolding tone, "Honey, if you forgot your keys, you should've called me. I would've come home and let you in."

I stared at the sweat on her forehead. When I spoke, my voice was cold as iron.

"Jess, did you ever give one of our spare keys to anyone else?"

Jessica froze mid-motion while taking off her shoes.

"What are you talking about? They're all in the drawer. Who would I give one to?"

Her tone was natural, but I immediately knew something was wrong.

Normally, Jessica wore a professional business suit to work.

But today, underneath her black blazer, she had on a low-cut camisole I'd never seen before. She'd even put on that limited-edition perfume she usually saved for special occasions.

Thinking about the man who might still be hiding in my bedroom, my heart sank.

I didn't rush to confront her. Instead, I spoke casually.

"The locksmith told me our lock comes standard with six keys. But I looked everywhere, and I only found five."

Jessica opened her mouth. "Maybe we remembered wrong when we bought the lock. Or maybe it came with an extra promo key or something. You can't expect to remember every little detail."

She turned and hurried toward the kitchen, trying to cover her nerves by keeping busy.

"Is that so? But I just checked the security camera. Kyle was here."

Jessica whipped her head around. The smile she forced onto her face looked more like she was about to cry.

"What are you talking about? Didn't Kyle move overseas three years ago? You must have misidentified him."

She walked over quickly and tried to grab my hand.

I stepped back and avoided her reach, letting out a cold laugh.

"Misidentified him?"

I pulled up the footage on my phone and held it in front of her face.

"Then tell me what this is. Are you going to say Kyle stole your key, got a copy made, and snuck into our house while we were both at work?"

As I spoke, I walked toward the bedroom.

"Whoever's in there — come out. Stop hiding. I'm giving you two minutes to get out on your own. Otherwise, I'm calling the cops."

The moment she heard the word "cops," Jessica got frantic.

She tried to snatch my phone away. "Honey, let me explain. It's not what you think."

I ignored her.

When the bedroom door still didn't open, I lost it and kicked it in.

But the bedroom was empty.

I couldn't believe it. I threw open the closet.

Still empty. I even checked outside the bedroom window. No sign of Kyle.

But how was that possible?

I went to pull up the footage on my phone again, but Jessica grabbed it and smashed it on the floor.

"I told you — you've just been stressed and seeing things. Are you done making a scene yet?

"Mark, I can't believe you'd suspect me like this after everything we've been through. You've really let me down."

I pressed my fingers against my temples. My head was spinning.

Was I wrong?

But the sixth key and Kyle's figure on the security footage were both telling me otherwise.

I wasn't mistaken.

But just as I bent down to pick up my phone, the strong scent of perfume hit my nose again.

Wait.

The bedroom window was wide open. The smell should have dissipated by now.

Unless the source of the smell was still in the room.

I ignored Jessica's yelling and fixed my eyes on the long bed skirt that touched the floor.

"Mark, are you done yet? How much longer are you going to act crazy?"

Jessica rushed over and tried to push me toward the door.

The more nervous she got, the harder she shoved.

I threw off her hand, crouched down fast, and yanked up the bed skirt.

The space under the bed was empty — just a few dusty storage bins.

Jessica let out a cold laugh.

"Mark, do you have anything in your head besides obsessing over my ex?"

I didn't say anything. I just stared at the storage bin all the way in the back, under the bed.

It was a clear plastic bin, filled with off-season bedding. But tucked into the folds of the white silk comforter was the corner of some black fabric.

A man's dress pants leg.

He'd climbed into the biggest storage bin.

This old-style bed had a lot of space underneath. If the bin was deliberately left slightly open, hiding a grown man for half an hour wouldn't be a problem at all.

I stood up. Instead of exposing him right away, I nodded along with what Jessica had said.

"Maybe you're right. I've been working too much lately. I'm sorry, babe. I was being too sensitive.

"To make it up to you, I'll cook tonight. Honey, can you boil some water for me?"

Out of the corner of my eye, I saw the bed skirt trembling slightly. I laughed to myself.

'Kyle, if you want to play hide-and-seek, I'll raise the stakes.'

Jessica clearly didn't want me staying in the house.

She grabbed my hand. "Honey, you've had a long day. Let's just go out to eat."

I looked at the desperation on her face, smiled, and casually sat down on the edge of the bed.

I clearly felt the mattress shift slightly.

The person inside the bin had probably adjusted their weight without thinking because of the uneven pressure.

"Going out is such a hassle. We already have food at home. Actually, babe — I'd love a cup of your signature homemade tea."

As I spoke, I leaned back heavily against the bed, putting half my body weight directly over the bin where Kyle was hiding.

Jessica clenched her jaw and took a deep breath. "Fine. Then go outside. The bedroom's a mess. I need to clean up."

"No need to clean. I'll just rest here."

I reached over to the nightstand and pulled out a small folding utility knife.

"Wh-why are you taking a knife?"

I savored the guilt written all over her face and said casually, "Got a hangnail. Need to trim it."

I fiddled with the blade, but my eyes stayed locked on the bed skirt touching the floor.

"I remember that bin has last year's silk comforter in it. I feel like there's a weird smell in here. Maybe the blanket's molding. We should take it out to air."

With that, I made a move to bend down and pull out the storage bin.

"Don't!" Jessica shrieked. "That's silk! You can't just put it in the sun. Mark, what is wrong with you today?"

I stopped and stared into her eyes.

"Honey, why are you sweating so much? Is it hot in here?"

She didn't answer. She just stood in front of me, frozen.

Seeing that, I still didn't let it go. I walked in with the electric kettle full of boiling water.

"If we can't air it out, then I'll pour hot water over the bed frame. Maybe that'll get rid of the dampness."

Jessica completely panicked.

"Don't!"

But it was too late.

The boiling water splashed over her hand. Her pale skin turned bright red in an instant.

Jessica yelped in pain and pulled her hand back.

The next second, I poured the entire kettle of boiling water directly onto the bed frame.

Steaming hot water ran down the frame and onto the storage bin.

Just then, a dull scraping sound came from inside the bin.

Then the bed skirt that had been trembling all along flew open.

A disheveled figure came crawling and scrambling out from under the bed.

"Mark, you're insane! I'm done playing!"