Dashiell is a 12-year-old boy living on Moon Base Alpha in the year 2041 with his scientist parents and younger sister. Dissatisfied with the mediocre food and confined reality of space travel, he pays close attention to the behaviors of the adults around him. He possesses a strong sense of curiosity and an ability to recognize patterns. When he overhears a mysterious conversation shortly before a doctor's death, he decides to launch his own investigation.

Kira is a sharp preteen who recently arrived at Moon Base Alpha with her father. She quickly displays an intense curiosity and a willingness to test boundaries. Instead of feeling intimidated by the rules of the base, she actively seeks out excitement and immediately offers to use her computer skills to assist Dashiell's investigation.

Nina serves as the Moon Base Commander, acting as the primary authority figure and representative of NASA. She carries the heavy responsibility of keeping the colony functioning smoothly while managing political optics back on Earth. She strictly enforces rules and actively works to shut down any rumors or investigations regarding Dr. Holtz's death.

Zan is a new security worker who has arrived on the base for a brief two-day stay. She has beautiful olive skin, long dark hair, and highly unusual eyes. Disagreeing with the official ruling on Dr. Holtz's death, she approaches Dashiell to covertly gather information on her behalf.

Dr. Holtz is the base doctor on Moon Base Alpha. He believes he has made a world-changing discovery and plans to share it with the colony. His sudden death on the lunar surface shortly after this claim serves as the catalyst for Dashiell's investigation.

Roddy is the only other adolescent on the base prior to Kira's arrival. He spends most of his time jacked into virtual reality, using an idealized avatar to play violent games and talk to girls on Earth. He possesses a cynical understanding of NASA's political motivations and demonstrates strong computer skills.

Chang is a lunarnaut on Moon Base Alpha with a history of conflict with Dr. Holtz over a supposedly stolen research idea. Despite this past grievance, he displays a willingness to defend the deceased doctor's honor. He is physically fit and possesses a strong sense of justice.

Lars is a wealthy tourist who paid a fortune to bring his family to Moon Base Alpha. He possesses a history of suspect business dealings on Earth and uses his money to avoid consequences. He frequently complains about the lunar experience and reacts with anger when embarrassed.

Patton is the spoiled, wealthy son of Lars and Sonja Sjoberg. As a tourist on the base, he behaves rudely toward the permanent residents. He frequently uses his size and his family's status to intimidate others.

Lily is the daughter of the wealthy Sjoberg family. Alongside her brother Patton, she acts entitled and mistreats the other adolescents on the base.

Dr. Marquez is the base psychologist, tasked with monitoring the mental health of the lunarnauts. He focuses heavily on maintaining a positive public persona and reacts defensively when questioned.

Garth serves as the maintenance worker on Moon Base Alpha. He maintains a quiet presence, often appearing silently behind other residents. He is notably excused from attending mandatory psychiatric evaluations with Dr. Marquez.

Daphne oversees the robotics operations on the base. She behaves strangely and avoids mandatory assemblies, choosing instead to covertly access administrative computer files.

Dashiell and Violet's mother works as a lunar geologist for NASA. She shares a portion of her scientific knowledge with her son while attempting to protect him from the harsher realities of the moon base.

Dashiell and Violet's father is a mining engineer recruited by NASA to live on the moon. He listens to his son's theories but ultimately defers to the official explanations provided by the base administration.

Violet is Dashiell's energetic younger sister. Due to her young age, she remains largely ignorant of the tensions and dangers present on Moon Base Alpha.

Riley is Dashiell's best friend back on Earth. She views the moon base as an exciting adventure, unaware of the difficulties and dangers Dashiell actually faces.

Eliza is Riley's sister on Earth. She rides along during calls to the moon base and treats Dashiell's new life with a lighthearted attitude.

Sonja is the wealthy wife of Lars Sjoberg and mother to Patton and Lily. She strongly disliked Dr. Holtz and is known to possess a temper.

Kira's father is a newly arrived lunarnaut. He is generally inattentive to his daughter's whereabouts but fiercely protective when a genuine threat arises.