Arriving in Southport with very little money, Erin uses the alias Katie Feldman to escape a highly abusive marriage to a Boston detective. She lives cautiously in a rundown hunting cabin, dyeing her hair and strictly guarding her privacy. Despite her deep-seated fears and reluctance to trust others, she possesses strong survival instincts and gradually opens up to the possibility of a new life.

Alex is the widowed owner of Fisher's, a local bait shop and grill in Southport. A former military Criminal Investigation Division detective, he is highly observant but left that life behind to raise his children in a small town. He is a patient, devoted father who carefully manages his grief while harboring a strong desire to rebuild his family and find companionship.

Kevin is a homicide detective with the Boston Police Department and Erin's abusive husband. He struggles with severe alcoholism and deeply ingrained insecurities, which manifest as violent, controlling behavior. Following his wife's escape, his personal and professional lives unravel as he becomes obsessively fixated on tracking her down.

Known to Katie as a perceptive neighbor and grief counselor who befriends her shortly after her arrival in Southport, she provides crucial emotional support as Katie builds her new life. Additionally, she is remembered as Alex's deceased wife, a devoted mother who passed away from an illness but left behind letters to encourage her family's future happiness.

Kristen is Alex's cheerful five-year-old daughter. She spends much of her time at the family store, occasionally helping at the cash register. Open and friendly, she is quick to form an attachment to the new woman in town, serving as an early bridge between her father and his new romantic interest.

Josh is Alex's seven-year-old son, currently finishing his first year of school. He enjoys fishing and outdoor activities with his father. Like his younger sister, he is welcoming to newcomers and misses the presence of a maternal figure in his life.

Bill is a captain with the Boston Police Department and Kevin's direct superior. He is practical and observant, successfully managing his department despite his subordinate's low opinion of his intelligence. He eventually recognizes Kevin's deteriorating behavior and takes disciplinary action.

Coffey is a detective in the Boston Police Department who works alongside Kevin. He is observant of his colleague's odd behavior and inadvertently exposes Kevin's lies about his wife's whereabouts to their captain.

Ramirez is a detective with the Boston Police Department working in the same division as Kevin and Coffey. He is a steady presence in the precinct, though Kevin frequently suspects him of engaging in workplace gossip.

Todd is a detective who becomes Kevin's partner after the retirement of Kevin's previous colleague. He is sociable and encourages Kevin to visit local bars after difficult shifts.

Karen is the daughter of Kevin and Erin's former neighbors in Boston. She unwittingly provides Kevin with a crucial piece of information about his wife's connection to her deceased sister, Katie.

Gladys is an older woman who lived across the street from Erin and Kevin in Boston. She provided a rare source of friendship to Erin during her isolated marriage.

Amber is a woman who frequents a local bar near the police precinct. She flirts with Kevin after a difficult shift, leading to a brief romantic encounter.

Joyce is a friend of Alex's in North Carolina. She asks him for a favor to help pick up her daughter at the airport, showing his integration into the local community.