A Pennsylvania chemical company executive, Tom Gruneman, has disappeared. The police reveal that an obscene letter was found in Gruneman's office, addressed to a prostitute in New York City named Bree Daniels, who had received several similar letters. After six months of fruitless police work, Peter Cable, a fellow executive at Gruneman's company, hires family friend and detective John Klute to investigate Gruneman's disappearance.