The Elevator

It was two in the morning. I was coming home late from overtime and walked into the apartment building's elevator. I was alone in the elevator. Just as the elevator doors were about to close, a pale hand suddenly reached in. A woman in a red dress, head bowed with her long hair covering her entire face, got into the elevator. I pressed the button for the twelfth floor. The elevator slowly ascended, and when it reached the fourth floor, it suddenly stopped. The doors opened, and there was no one outside. The woman suddenly spoke, "Can you see the person outside?" I was stunned and asked, "Who?" She slowly raised her head, revealing a face with no features. "The one standing behind you." I whipped my head around, but there was nothing there. The elevator doors closed. I frantically pressed the twelfth-floor button. Finally reaching my doorstep, I rushed out and immediately looked back. The elevator was empty. The next day, I asked the building manager about what happened last night. After hearing my story, his face instantly turned pale. "Sir, our building's elevator can only hold three people." I frowned. "What do you mean?" He pointed a trembling finger at the security camera. On the screen, I was seen entering the elevator alone, talking to the air. And in the corner of the elevator, a woman was slumped over my shoulder. The scariest part was... The security footage showed that someone had been following me even before I entered the elevator.