Carlos stood on the corner across from the entrance to the Central Park Zoo, watching the security guard flirt with every exiting nanny. Closing time was fifteen minutes away, too late to pay his way in. So he waited until a woman pushing a baby carriage bearing twins caught the guard’s attention. The guard blocked her path, dropped into a crouch, and began speaking in Spanish to the infants. Carlos washed past unseen, not four feet away. By the time the nanny escaped to Fifth Avenue, he was inside the zoo.