Mourning the passing of a family friend who has succumbed to a mysterious disease, Sarah and Frank work around their wedding preparations to unravel a web of secrets while exposing a Civil War-era crime and a present-day threat.

Detective Sergeant Frank Malloy and Victorian midwife Sarah Brandt join forces to find a young woman who goes missing after responding to "lonely hearts" ads in the newspaper.

Sarah Brandt and Sergeant Frank Mallloy scour Victorian Manhattan to investigate the death of a nursemaid who claims to know the birthmother of Sarah's daughter.