With his friend and lover Alexandria Shaw living in the bucolic little southwestern Maine town of Garrison while she writes a book, Boston lawyer Brady Coyne spends his weekends visiting her. One summer Saturday morning while driving the back roads, Brady meets Charlotte Gillespie, a middle-aged African-American woman. Charlotte is carrying a sick dog. Brady drives her to the veterinarian and back home again, where Brady sees that someone has painted a large swastika on a No Trespassing sign. When the dog later dies, probably of poisoning, Charlotte hints at something larger at play, something she can't discuss just yet.
The following weekend, Brady arrives at Alexandria's to find a letter from Charlotte, asking for his help. But when he visits her, he finds her house empty and another swastika spray-painted on her property. Charlotte seems to have disappeared without a trace.
To find out what has happened to her, Brady must first learn who Charlotte really is and what potentially dangerous secrets she knows.