"You know me, don't you?"

Those words. Her words. Forever etched into your soul.

"You know me. The faint voice in the back of your head."

And with them, the grotesque scenery. The rooftop covered with small, grey rocks and the city beneath it, with the bright lights of a carnival, cars passing by, the Ferris wheel steadily turning.

"You are standing on the huge cliff, absently staring at the landscape. What do you think? You would say you're admiring the beautiful nature. That's not true. It's what you would like to think. But there is me, in the back of your head, whispering into your ear. And you think — what if? What if you did it? What if you took that step? What would it feel like? How long will it take?
And you feel the itching, you feel my presence, you want to know. What if?"

The scene that haunted you for so long plays in front of your eyes again. Like an old Super 8 movie, with cracks and jumps and missing images, you see her again, on that day. It's raining, you remember that. She's there, sitting on some vent, looking at the city to her feet. And she's speaking these words. How could you ever forget them? Her voice sounds so different. Calmer, somehow.

"You know me," she says. "You are waiting for your train, on your way back home. There's a child near you, running around cheerfully. And you want to think about how cute that kid is or how old it might be or where it got the balloon it is holding. I know you do. But really, what you are thinking about is how easy it would be to push him. One smooth movement completed by the District Line arriving just half a minute later. What would happen? What if?"

The film is almost over. You don't want to see it again. You close your eyes. The film doesn't care. It continues to run vividly in your mind, every word echoing through your skull. She stood up by now, looks deep into your eyes, and slowly walks backwards, approaching the abyss behind her. You distinctively hear every step she takes, find yourself counting down.

"What if?"

The next few seconds of the film are black, burned away years ago. You see the people on the street below screaming, forming a circle around a vaguely humanoid shape on the ground. You turn away. The film is over.
And now you are here on the edge, just as she said, and think to yourself.
What if?