At ten years old, Emma sees the world through numbers and logic, using her analytical skills to help unravel puzzles related to their mother's whereabouts. Her rational mindset is challenged by the unfolding mystery.

Eight-year-old Finn is adventurous and impulsive, often seeing their predicament as an exciting game. His youthful perspective and bond with his mother drive his actions during their quest.

Kate is the mother of Chess, Emma, and Finn, enigmatic due to the story being told through the children's eyes. Her disappearance sets off the events of the plot.

Thirteen-year-old Natalie, daughter of the woman caring for the Greystone children, evolves from a sullen teenager to a valuable ally as she becomes curious about the unfolding mystery.

Natalie's mother, tasked with caring for the Greystone children, she is depicted as a hardworking single mother who juggles her responsibilities while trying to connect with her daughter.

A mysterious character first known as a voice on the phone who assists the children with navigating challenges in an alternate universe. His role is to guide and provide essential exposition.