As I left my job at the stockbrokerage on the 72nd floor of the 1 World Trade Center building, I put the wireless earbuds in. By the time the express elevator started moving, I was grooving to a Cree Summer oldie playing off my iPhone.

But as the elevator started slowing as it passed the last real floor before the lobby, the music cut out. “Hey!” I fished the phone out of my pocket and eyed the screen. It was blank. I squeezed the buttons for a reset, but nothing happened.

I sighed. “Oh well, at least it’s still under Applecare.”

I was halfway to the subway when a female voice spoke from the earbuds that I hadn’t bothered to take out. “Don’t look behind you. You’re being followed.” Naturally, I started to turn my head, but stopped with a wince when the voice yelled, “Don’t!”

“What the—?” I pulled out my iPhone again. Instead of the desktop, there was…a face? A pretty girl with brown hair and a worried expression.

“Please—just keep walking,” she said. “I’ll help you lose them, then I’ll explain.”