Successful Marin County, Ca financier, Andy Barlow, is training in the cold San Francisco Bay for a competitive open water swim. Unexpectedly, his support boat runs him over midstroke, killing the swimmer instantaneously. Consumed with grief and anger, Andy's college-aged son Harrison, returns from London to probe what really happened. Although the local sheriff's office calls the tragedy an accident, Harrison refuses to believe their findings. He reaches out to amateur sleuth Trisha Carson to hunt down the real killer.

Trisha digs into the man's history and finds fractured relationships in his family, his business and his marriage. There's clearly more than one person who had reason to seek a deadly revenge, but would they go as far as murder?