Just months after Michael Cunningham’s three-part Specimen Days comes another novel — Ghost Town — that attempts to capture the restless spirit of New York City through the ages in an elegant and compact trio of spooky stories. In the haunting ”Year of the Gibbet,” a Revolutionary-era boy watches as his patriot mother is forced to strip for an effete British soldier, who subsequently hangs her. Almost a century later, in ”Julius,” another beautiful New Yorker takes her clothes off — voluntarily, for an art class — igniting the passion of an unstable young man and triggering the decline of his powerful family. And in the cool, contemporary ”Ground Zero,” an unreliable psychiatrist narrator describes a patient’s seemingly twisted affair with a prostitute following 9/11. The three tales don’t add up to a richly satisfying portrait of a great city, but their febrile longings, grief, and, above all, loneliness make a compelling snapshot.