Mick is a 42-year-old murder detective with the Dublin Murder Squad. He maintains a high solve rate and pays meticulous attention to his personal presentation, preferring tailored suits and a neat appearance. He operates under the strict belief that victims usually invite crime into their own lives through poor choices. A deep childhood trauma drives his intense need for control and order.

Richie is a young, newly minted detective undertaking his first major murder investigation as Mick's trainee. Coming from a rough, lower-class background, he possesses a restless energy and a natural talent for making people feel comfortable during interviews. Unlike his mentor, he approaches cases with a deep sense of empathy for the victims and believes bad things can happen to anyone.

Jenny is a stay-at-home mother dedicated to maintaining a perfectly clean home and raising her children with organic, homemade meals. She relies heavily on outward appearances to project stability while living in the nearly abandoned Ocean View housing estate. Following a violent incident in her home, she survives in critical condition while police try to piece together her family's final days.

Pat is a dedicated family man who recently lost his job due to the economic recession. He moved his family into a new housing development during the economic boom to provide a perfect life for his wife and children. As financial pressures mount, he spends his time searching the house for an imagined animal intruder.

Conor is a freelance web designer and a long-time friend of Pat and Jenny who lost touch with them after criticizing their decision to buy their house. He struggles to find work during the economic downturn and spends his time secretly observing the Spains' neighborhood. He emerges as a central figure in the investigation due to his proximity to the crime scene.

Dina is Mick's youngest sister. She lives with severe mental health challenges and frequently arrives unannounced at her siblings' homes during periods of intense emotional turmoil. Her erratic, unpredictable behavior heavily contrasts with her brother's rigid need for order and professional distance.

Fiona is Jenny's sister and an independent photographer living with roommates in Dublin. She actively rejects societal expectations regarding wealth and appearances, creating a contrast with her sister's lifestyle. She alerts the police to perform a welfare check on the Spains after Jenny misses their daily phone call.

Geri is Mick's highly responsible other sister. She works as an accountant for an interior design company and raises three children with her husband. She frequently serves as a stabilizing force and practical caretaker for her siblings.

Emma is the young daughter of Pat and Jenny Spain. She lives in the isolated Ocean View estate and absorbs the growing tension in her household. Her crayon drawings provide subtle clues to the detectives regarding her final days.

Jack is the youngest child of Pat and Jenny Spain. He relies entirely on his parents for care in the increasingly tense environment of their unfinished housing estate.

Superintendent O'Kelly is the commanding officer at the Dublin Murder Squad. He oversees detective assignments and expects swift, clean resolutions to major crimes.

Dr. Cooper is the pathologist assigned to the Spain family murders. He exhibits a noticeable dislike for Mick and strictly limits the information he provides before official postmortems.

Larry is a blood spatter expert working with the Bureau. He provides critical physical evidence to help Mick and Richie piece together the sequence of events during the attack.

Sinéad is one of the few neighbors living near the Spains in the unfinished estate. She attempts to protect her young son from police scrutiny while withholding minor details about the neighborhood.

Jaden is the ten-year-old son of Sinéad Gogan. He explores the abandoned houses in the unfinished estate and inadvertently crosses paths with strangers in the neighborhood.

Quigley is a fellow detective on the squad who openly dislikes Mick. He takes pleasure in Mick's professional difficulties and criticizes his focus on personal appearances.

Laura is Mick's ex-wife. She ended their marriage because she desired to start a family, a life path Mick firmly rejected due to his own childhood trauma.