Tristan McGowan is the son of an infamous Irish mobster who returns home for the internment of his mother's ashes. He discovers that his sister is missing and takes on the role of tracking down the gang responsible for her kidnapping, uncovering a dark family secret in the process.

The sister's disappearance is the central plot element that drives the story. It prompts Tristan McGowan to investigate and confront the gang responsible, which leads to the revelation of a dark family secret.

Key mobster characters include Tristan McGowan, the son of the infamous Irish mobster; Duke Angel, an American mobster laundering money through mob boss Brandon McDonnel; and Velma Angel, Duke's wife. Brandon McDonnel is the mob boss connected to the laundering operation.

While the exact details are not fully disclosed, Tristan McGowan uncovers a dark family secret related to his family's criminal background and the circumstances surrounding his sister's kidnapping during his investigation.

Irish Ashes was filmed in the United Kingdom, including Nottingham, England near Nottingham Castle. The setting provides a backdrop that supports the crime and mobster themes of the story, grounding the narrative in a realistic environment tied to the characters' backgrounds.