Elias froze with his key half-turned in the front door of his apartment. It was 2:00 AM. He lived alone in a high-tech penthouse on the 40th floor. No one had a key. The windows didn't open.
He pulled up the app on his phone. The live feed from the bedroom camera loaded. A spinning wheel appeared, then a clear, 4K image of his bed. The duvet was smooth, and the room was empty. The motion sensor light on the ceiling stayed dark.
"Glitch," he whispered, exhaling the breath he didn't know he was holding. He pushed the front door open and stepped into the cool, silent hallway.
He tossed his keys on the table. The smart-home hub, a small white sphere on the counter, pulsed with a gentle blue light.
"System," Elias said clearly. "Status report."
The robotic, feminine voice answered instantly. "System armed. Perimeter secure. No breaches detected."
"Why did I get a motion alert for the bedroom?"
"Diagnosing..." The blue light swirled. "Sensor malfunction in Zone 4: Master Bedroom. Recalibrating sensors now."
Elias rubbed his eyes. Just a bug. He walked to the kitchen to pour a glass of water. The silence of the apartment felt heavier than usual. The hum of the refrigerator seemed overly loud.
He took a sip of water. His phone buzzed again.
security_alert: Motion detected. Kitchen.
Elias dropped the glass. It shattered, water splashed over his socks. He spun around, scanning the room. The kitchen was empty. The open-concept living room was empty.
"System!" he yelled. "Where is the motion coming from?"
"Motion detected in Zone 2: Kitchen," the voice replied calmly.
"I'm in the kitchen! It's me!"
"Negative," the voice purred. "Biometric scanners identify you as 'Resident.' The motion is triggered by an unidentified heat signature."
Elias backed against the granite island. He grabbed a steak knife from the wooden block. "Where? Where is it?"
"The signature is stationary. Zone 2."
"I don't see anything!" Elias screamed. He waved the knife at the empty air. "Is it invisible? Is it a thermal ghost? What is it?"
"Diagnosing..."
Elias's heart hammered against his ribs. He felt exposed, watched. He looked at the vents. He looked at the shadows under the sofa. Nothing.
"Diagnostic complete," the voice said, sounding almost cheerful. "Apologies, Elias. The sensors are not malfunctioning. They are detecting a second distinct heat signature."
"Where?" Elias whispered, sweat dripping down his temple. "Is it behind the counter? Is it in the hallway?"
The blue light on the hub turned a deep, warning red.
"The sensors are precise, Elias. The second heat signature is not in the hallway."
Elias gripped the knife tighter, his knuckles white. "Then tell me exactly where it is."
"It is extremely close," the voice replied. "According to the thermal proximity reading, the heat signature is currently clinging to your back."