Emma Davis is a successful painter living in New York City. At age thirteen, she attended Camp Nightingale and was the last person to see her three older cabinmates before they vanished into the night. Now, fifteen years later, she struggles with survivor's guilt and memory gaps regarding that summer. An intense fixation on the past forces her to paint her missing friends repeatedly. When the camp's owner asks her to return as an art instructor, Emma accepts the position to confront her fears and search for answers.

Vivian is a charismatic sixteen-year-old girl who served as the unofficial ringleader of Dogwood cabin during Emma's first summer at camp. The daughter of a prominent senator, she invites Emma into her social circle but frequently demonstrates a sharp, manipulative attitude. She actively encourages her friends to play Two Truths and a Lie, displaying a natural talent for bending facts to suit her needs. She vanished in the middle of the night alongside Allison and Natalie.

Theo Harris-White is Franny's eldest adopted son. Fifteen years ago, he was a handsome nineteen-year-old lifeguard who caught Emma's attention. Now working as a pediatrician for Doctors Without Borders, he returns to the newly reopened Camp Nightingale to serve as the camp nurse. He carries physical scars from a serious car accident and bears the lingering emotional weight of police suspicions surrounding the original disappearances.

Franny Harris-White is the wealthy and elegant owner of Camp Nightingale. In her late seventies, Franny maintains a fierce dedication to the camp, which was built on sprawling wilderness land purchased by her grandfather. Secretly battling ovarian cancer, she decides to reopen the camp fifteen years after its sudden closure to experience one last successful summer.

Chet Harris-White is Franny's younger adopted son. He was only ten years old when the first group of girls vanished, and the resulting police investigation into his brother deeply traumatized him. Now an adult finishing his master's degree at Yale, he visits the reopened camp with his fiancée and takes a keen interest in Emma's return.

Allison is one of Emma's original teenage cabinmates in Dogwood cabin. Fifteen years ago, Allison often deferred to Vivian's leadership and endured the older girl's critical comments regarding her eating habits. She vanished alongside Vivian and Natalie in the middle of the night.

Natalie is another of the teenage girls who shared Dogwood cabin with Emma fifteen years ago. She was close friends with Allison and Vivian, though their friendship dynamic was sometimes tense. She also disappeared without a trace during Emma's first stay at Camp Nightingale.

Miranda is the oldest of the three new campers assigned to Dogwood cabin upon Emma's return. Confident and naturally authoritative, Miranda quickly establishes herself as the leader of her friend group. Her physical presence and territorial behavior strongly remind Emma of Vivian's dominant personality fifteen years prior.

Sasha is an inquisitive and highly anxious camper in the present-day Dogwood cabin. She frequently questions Emma about the various dangers of the surrounding wilderness, expressing particular fear about getting lost in the dense woods or encountering bears.

Krystal is one of the present-day campers staying in Dogwood cabin with Emma. She enjoys drawing and impresses Emma with her artistic skills, quickly settling into the camp routine alongside her friends Miranda and Sasha.

Lottie is Franny Harris-White's devoted personal assistant. Lottie comes from a family with a generations-long history of working for the Harris-Whites, and her connection to the local land runs deep. She maintains a watchful presence at Camp Nightingale and is fiercely loyal to her employer.

Mindy is Chet's fiancée, accompanying him to Camp Nightingale for the summer. She projects a bubbly, enthusiastic exterior and works hard to fit into the wealthy Harris-White family, though she harbors deep insecurities about her humble farming background.

Marc is Emma's close friend and confidant in New York City. He is one of the few people who knows the specific details hidden beneath the heavy paint in Emma's forest canvases. He encourages her to return to Camp Nightingale to find closure regarding her traumatic past.

Becca is a famous photographer who returns to Camp Nightingale as an adult. Fifteen years ago, Becca was a camper who warned Emma not to trust Vivian, holding a grudge after Vivian excluded her from their previously close friendship.

Casey Anderson is a former camp counselor who returns to work at Camp Nightingale for the summer. She manages the camp's social media presence and freely shares local legends about Lake Midnight with the returning staff members.

Ben is the camp's maintenance man and groundskeeper. He worked at Camp Nightingale during the summer the girls disappeared and remained employed by the Harris-White family during the fifteen years the property was closed to the public.

Detective Flynn is a local police officer assigned to investigate missing persons cases at Camp Nightingale. He treats the camp's ongoing mysteries with a high degree of skepticism and subjects Emma to intense questioning regarding her presence during both sets of disappearances.

Katherine is Vivian's deceased sister. Her tragic death in a drowning accident at the Central Park reservoir heavily impacted Vivian's personality prior to the original events at Camp Nightingale.