Dubliner Sarah Manning's husband Lee is murdered while in Montreal on a business trip. Devastated, she accepts solace from his company, where she also was employed. The Irish Garda works with Montreal police to solve his murder, while Sarah realizes she knows very little about her dead husband except he was born in Chicago. The police are curious if Sarah's first husband's death was truly the accident it was believed to be.

Canadian police, a German investigator, and local Garda try to piece together the puzzle of Lee Manning's death as it is connected to an American operation that was keeping tabs on him and his family. Meanwhile Sarah and her sister get deeper into the mystery when a shady character enters their lives and Sarah suspects the drug company's secrets are behind what happened.

As DS Byrne digs further into Lee Manning's death, her superior removes her from the case, ostensibly to further her career with a training course in London. Sarah's sister tells Sarah that she thinks Lee was trying to find out about Sarah's first husband, and maybe their meeting and ensuing romance was planned by him with an ulterior motive.

DS Byrne decides to put her career in jeopardy by defying her boss and continuing the investigation. She teams up with Sarah who discovers evidence linking the huge drug company with politicians and the Garda and confronts high level employees at the drug company, leading to another death.

The investigation into Lee and Ciaran's deaths is reopened after DS Byrne's superior tells her he is retiring to spend more time with his ailing wife. Sarah confronts Hoffman but is rebuffed, after which he hints to authorities that she is an unfit mother. Sarah also confronts her sister and her ex-brother-in-law about the file containing information about real estate dealings the then married couple were involved in.

Dr. Hoffman strong-arms an American diplomat into terminating the FBI investigation being run from the US Embassy. Meanwhile Sarah forces her sister Nuala to disclose what was going on with a piece of property that lead to Ciaran's death. The property was formerly a home for unwed mothers and Sarah and DS Byrne uncover the reason Hoffman and the company were willing to kill to keep a 25-year old secret, but Hoffman manages to get on his private jet before he could be detained.