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 30 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 30 years of visiting car license plates. He started the "diary" after the first murder. The DNA that the Pennsylvania police gather matches the remains in the Maryland case. Heather unravels the DNA connection and locates both murder weapons. Henry's twin brother Arthur writes a deathbed letter identifying whom 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.