Shanna McGuire is convinced a strange man is following her. When he approaches her on the street, he shocks her with a story that makes her question her family history. She asks Simm to investigate the man's claim. A simple case of genealogy and the search for a possible treasure are perfect for Simm, a former private investigator, and his wife Charlie, both pub owners in Downtown Montreal.

Simm's research uncovers a dark period in Quebec's past when unwanted babies were left in orphanages to suffer years of abuse and deprivation. Decades later, the corruption of the era is revived as the straightforward case takes a dangerous turn with threats, violence, and homicide.

Charlie and Simm question the wisdom of carrying on when their lives and the lives of those around them are threatened. Determined to see it through, the couple fights to sever the web of lies and betrayal to discover the link between seemingly-interconnected crimes while racing against the clock to avert another murder.

A Stranger in the Family reunites readers with the popular husband-and-wife team of Charlie & Simm, created by A.J. McCarthy, the award-winning author of Sins of the Father and The Other Side.