Antoinette is a rookie detective on the elite Dublin Murder Squad and the only female and biracial detective on the team. She carries a permanent chip on her shoulder due to constant hazing and isolation from her colleagues. Growing up without a father deeply shaped her cynical worldview and her fierce determination to handle problems independently. She brings an aggressive, street-smart approach to her investigations.

Steve is a 33-year-old rookie detective on the Murder Squad who looks younger due to his gangly build and orange hair. His relentless cheerfulness and desire to please others contrast sharply with Antoinette's abrasive nature. He maintains a loyal partnership with Antoinette, often using his affable personality to secure information and contacts that she cannot access.

Aislinn is the murder victim at the center of the investigation, found with a cracked skull in her meticulously prepared apartment. Once a dowdy, sheltered woman who devoted her youth to caring for her traumatized mother, she recently transformed herself into an attractive, polished trophy girlfriend. Her past is marked by her father's disappearance, an event that halted her personal development for years.

Breslin is a senior detective on the Murder Squad who projects an aura of superiority and professional success. He drives a flashy BMW, boasts about his children attending private school, and exudes supreme confidence. He takes an aggressive approach to interrogations and constantly attempts to dictate Antoinette and Steve's investigation.

Rory is Aislinn's new boyfriend, a young man who works in a bookshop and looks younger than his 29 years. He wears old glasses with cloudy frames and possesses fine, pointy features that make him appear extremely nervous. The detectives immediately suspect him after finding texts indicating he was supposed to visit Aislinn on the night she died.

Lucy is Aislinn's best friend, described as short and fit with a pale face and quick features. She is highly protective of Aislinn's memory and carefully curates the information she shares with the police. She provides the detectives with crucial background on Aislinn's sheltered upbringing and subsequent dramatic physical transformation.

McCann is a nondescript, middle-aged detective on the Dublin force who is beginning to develop a paunch. He carries permanent eye bags and a heavy five o'clock shadow, giving him the appearance of constant exhaustion. He previously worked in Missing Persons, where he handled the investigation into Aislinn's father's disappearance.

O’Kelly is the gruff, no-nonsense chief of the Dublin Murder Squad. He projects the image of an outdated, fussy administrator who cares deeply about his office nameplate and stash of single malt, but he is actually a sharp and demanding leader. He requires regular updates from his detectives and commands their cautious respect.

Crowley is a sensationalist newspaper reporter who actively undermines Antoinette's reputation in print. He cultivates a specific look with floppy shirts, a dandruff-spotted coat, and a dark ponytail covering a bald spot. He uses leaked police information to paint the detectives as incompetent while masquerading as a crusader for truth.

Desmond is Aislinn's absent father who vanished when she was twelve years old. His sudden disappearance traumatized his family, causing his wife to suffer psychological issues and forcing Aislinn to put her own life on hold while hoping for his return.

Evelyn is Aislinn's mother, who developed severe psychological problems after her husband abandoned the family. She required constant care from her daughter, effectively halting Aislinn's personal development until Evelyn passed away.