The Condensation

The duplexes on Maple Row were packed so tight that the shared firewall had become a membrane, a thin, sweating boundary between my living room and the Wallers’ kitchen. I’d grown up with their complaints—the too-loud TV, the phantom footsteps, the smell of their fish stew seeping through the cracks. But yesterday, the membrane peeled back.

My new air conditioner arrived on Tuesday, a massive window unit with a compressor like a steel heart. The old one had been a wheezing relic, and its hole was too small. So I spent the morning with a chisel and hammer, knocking out bricks, sending dust motes spiraling into the humidity. The Wallers’ side was silent, which I should have known was wrong. They always had something to say.

By noon, I had the unit wedged into the frame, its vents aimed inward. I plugged it in, and the machine shuddered to life, blowing cold air that tasted like tin. The room began to cool, but within minutes, a dark stain bloomed on the firewall, right where the unit’s back panel pressed against the brick. I touched it—wet, greasy, like cold sweat. It spread, forming a rough outline of a rectangle, the exact size of my new machine.

I wiped it with a rag, but it returned within seconds, darker, almost black.

That’s when the real noise started.

At first, I thought it was the compressor’s thrum, but then I realized the sound was coming from the wall itself—a low, rhythmic thumping, like a giant heartbeat. It matched the pulse of the AC. Then came the scratching, faint but distinct, as if something on the other side were raking its fingernails down the bricks. I pressed my ear to the damp plaster and heard a voice, muffled but unmistakable—Mrs. Waller’s voice, but twisted, like a record played at the wrong speed.

‘We know you’re there, Ethan.’

I yanked the power cord, silence. The room fell into a stifling heat, but the stain remained, now a dark, glistening patch that seemed to pulse with its own life, slow and steady. I called the landlord, who said they’d ‘look into it.’ He never did.

That night, I couldn’t sleep. The AC sat dead in the window, a cold hulk. Around 2 AM, I heard a click—the unit’s thermostat, even though it was unplugged. Then the fan started spinning, slow at first, then faster, whirring without power. I watched, frozen, as the machine turned itself on, blowing a stream of ice-cold air directly at the stain. The stain rippled, and the scratching returned, louder, more frantic, like a thousand claws on the other side.

Then the voice came through the vents, not muffled now but clear and sharp, as if Mrs. Waller were standing inside my room.

‘You took our space, Ethan. You sealed it up with your machine. Now we’ll take yours.’

I stumbled backward, and the room changed. The walls began to sweat, beads of water rolling down like tears. The ceiling dripped, and the floor grew slick. I slipped, fell, and when I looked up, the stain had spread across the entire firewall, and it was no longer a stain—it was a window. Through it, I saw Mrs. Waller’s face pressed against the glass, but her skin was gray, peeling, and her eyes were empty sockets, black and wet. She smiled, and her mouth kept opening, wider and wider, until it was a cavern filled with crawling things.

I scrambled to the front door, but the handle was wet and cold, and it wouldn’t turn. The AC hummed louder, and the room began to shrink, the walls closing in, the ceiling descending. The condensation poured now, turning the air to thick fog. I could hardly breathe, and the smell—damp, rotten, like something left to fester in a locked room—filled my lungs.

‘You should have checked the drainage line, Ethan,’ Mrs. Waller’s voice echoed from every direction. ‘All that excess moisture has to go somewhere.’

I screamed, and the sound was swallowed by the roaring of the compressor, which was now screaming like a wounded animal. The firewall bulged, and I knew it was about to burst, to spill whatever was on the other side into my room. I thought of Lucy, of her warnings about the Wallers, but she was gone.

I woke up this morning on the floor, soaked to the bone. The AC was off, and the stain had vanished, leaving only a faint, greasy smear. But the wall behind it is softer now, spongy to the touch. And when I put my ear to it, I can hear my own heartbeat, thumping back at me, syncopated and wrong.

The Wallers haven’t complained today. They haven’t made a sound. But I saw Mrs. Waller in the backyard, staring through my kitchen window, and her lips were moving. I couldn’t hear her, but I could read the words: ‘We’re all installed now.’

My new AC is still on the floor, unplugged. I’m afraid to throw it away. I’m afraid of what I’ll find in the pipe if I do.