“You could start explaining right now,” I said, as I jogged down the stairs into the subway station. “Perhaps you could begin with ‘who the hell are you and what are you doing in my iPhone?’”

“My name is Nicolette, you can call me Nicky,” she said.

I went through the turnstile without stopping. It beeped as it scanned my ID chip and debited the fare from my account. “Nice to meet you. Why are you in my phone?”

“I’m—I was the operator of the Aegis intel outpost on the 19th floor of 1 WTC,” Nicky said.

“But there is no 19th floor,” I replied. “Everything between 6 and 20 is just part of the tower’s base.”

“That’s what the plans say,” Nicky said. “But there are things they don’t show. Oh—turn left here, ignore the ‘keep out’ signs.”

I looked dubiously at the unfinished passage festooned with barriers and hard-hat-area notices. “Are you sure?”

“Once you get past the signs, run. Get me to the door at the end. Hurry!”

Not even sure why I was doing this, I ducked past the barriers and began to run.