The hall man, in turn, passed me off to an elevator man. Upstairs, a diminutive butler waved me in through the open door of 10 B.

Through the nearly double-height French doors, I could see the whole way through the Dunnings’ apartment to Central Park. The grand rooms were arrayed in the classic enfilade design, allowing more than one way into each room so guests could avoid the servants. The wood floors, like the paneled walls, were Cuban mahogany. They were laid out in a herringbone pattern with what looked like a black-walnut trim.

A striking black-haired woman came quickly down the long corridor of the apartment. She was wearing a rumpled blue evening dress, and even from a distance, the agony in her fine-boned face was unmistakable. My annoyance at being called in dissipated as my heart went out to her. Even with her elegant clothes and her surroundings, she was just a concerned mom sick with worry.

“Thank God you’ve come. Detective Bennett, is it?” she said with an English accent. “It’s my son, Jacob. Something’s happened to him.”

“I’m here to help you find him, ma’am,” I said as reassuringly as I could while I took out my notebook. “When was the last time you saw or spoke to Jacob?”

“I spoke to him three days ago. Jacob lives at school. At NYU. Hayden Hall, right alongside Washington Square Park. My husband is still down there with my father. They’ve spoken to his friends, and no one has seen him since Friday. Not his roommate. No one.”

Maybe he met a cute girl, I felt like saying to her.

“Not seeing someone for a few days might not necessarily mean something’s wrong, Mrs. Dunning. Is there a specific reason why you think something’s happened to him?”