Heather Macy returns home to become a partner in her father's law firm in a city in southern Pennsylvania. Macy House is in a village across the Mason-Dixon line in Maryland. Heather's father, W. Henry Macy, inherited the General's Farm in 1973. The M-D line happens to run through it. Heather encounters two simultaneous murder investigations. The murders, separated by thirty years, were committed on the same spot, but the bodies were buried on opposite sides of the border. Heather meets a hermit who has been keeping a record for thirty years of visiting car license plates. He started the diary after the first murder. The DNA that the Pennsylvania police gathers matches the remain in the Maryland case. Heather unravels the DNA connection and locates both murder weapons. Henry's twin brother, Arthur, writes a deathbed letter identifying who, he believes, committed the 1973 murder. Some arrests are made. One testimony triggers a series of conspiracy confessions by others. One of the 2003 license plate numbers is an accurate but misleading clue.
