Cal is a 48-year-old former Chicago police officer seeking a quiet early retirement in the rural Irish village of Ardnakelty. Divorced and hoping to escape the complexities of his past career, he wants a simple life of fishing, rabbit hunting, and home repair. He possesses strong, ingrained police instincts that he struggles to suppress when mysteries arise in his new home.

Trey is a scrawny, tough 13-year-old from the socially isolated Reddy family. Fiercely determined and deeply loyal, Trey approaches Cal with a demand to investigate a missing older brother. Mistrustful of the local authorities and townspeople, Trey is resilient, resourceful, and capable of surviving in the harsh rural environment.

Brendan is Trey's 19-year-old older brother who disappeared six months prior to Cal's arrival in Ardnakelty. Intelligent and possessing a talent for chemistry and engineering, Brendan lacked the grades for college and instead focused his energy on ambitious schemes to make money. He acts as a surrogate protector for his younger siblings in their father's absence.

Mart is Cal's 61-year-old neighbor and a prominent member of Ardnakelty's older generation. Garrulous and sociable, Mart is a fixture at the local pub and takes an immediate interest in Cal's presence. He portrays a chatty, friendly demeanor while subtly advising Cal on how to fit into the local culture.

Sheila is the estranged wife of Johnny Reddy and mother of six children, living in poverty on the outskirts of the village. Once considered a local beauty with plans to become a nurse, she is worn down by years of hardship. She is guarded around strangers and suffers the brunt of the community's malicious gossip.

Noreen is the local convenience store owner in Ardnakelty and sister to Lena Dunne. She serves as a central hub for village gossip, carefully monitoring who buys what and distributing her approval or disapproval accordingly.

Lena is Noreen's sister and a tall, attractive widow who works doing the books for a horse stable. Fiercely independent, Lena refused to continue farming after her husband's death, preferring autonomy over community expectations. She is pragmatic, direct, and compassionate toward local outcasts.

Donie is a hot-headed 25-year-old local who attempts to project an intimidating, gangster-like persona. Living with his mother, Donie holds lingering resentments toward Brendan Reddy and boasts connections to a Dublin-based drug operation.

Caroline is Brendan Reddy's sensible and ambitious ex-girlfriend. She works part-time while preparing for a career in hotel management that she hopes will allow her to travel away from Ardnakelty. She provides Cal with a positive, grounded perspective on Brendan's character.

Fergal is a young local farmer and friend of Brendan Reddy. Pleasant but stubborn, Fergal adheres closely to the traditional, land-tied lifestyle of Ardnakelty's older generation and insists he knows nothing about Brendan's disappearance.

Alyssa is Cal and Donna's 25-year-old daughter who lives in Seattle, Washington, and works for a non-profit helping at-risk teenagers. Her relationship with Cal is strained following an incident years earlier, leading to distant and cautious phone conversations.

Donna is Cal's ex-wife, who left him for another man after a series of arguments regarding their daughter. She remains a critical, doubting voice in Cal's mind and maintains a guarded, formal tone during their phone interactions.

Eugene is a wealthy, college-attending friend of Brendan Reddy. He is obsessed with motorbikes and holds a somewhat selfish, judgmental attitude toward Brendan's lack of formal education.

Johnny is Sheila's estranged husband and the father of the six Reddy children. Known for having grand ideas but failing to execute them, Johnny abandoned his family to travel to London.

Garda O'Malley is a local police officer stationed in the nearby town of Kilcarrow. He shows little interest in investigating Brendan Reddy's disappearance, assuming the young man simply left for the city.

Ben is Alyssa's boyfriend in Seattle. Cal describes him as an annoyingly earnest young man who is heavily involved in social causes.

Elliot is a man from Donna's book club whom she began a relationship with after leaving Cal.