“It is a tracking unit,” Sloan said, sliding the plastic cover back to reveal a small green light that blinked once every five seconds.

“It runs on a small cellular battery.”

The green light flashed against the grey skin of her palm.

“He has been watching my route,” I said.

“He knows when you leave the hospital,” Sloan said.

“And he knows when you arrive at your apartment.”

I reached out and touched the cold plastic of the box.

“How long has this been on my car?” I asked.