Jonathan is a 12-year-old boy who loves baseball and outdoor activities. As an older brother, he wrestles with the frustration of adjusting his walking pace for his sister's mobility issues while harboring deep compassion for her condition. When disaster strikes their camping trip and separates them from their parents, he finds himself thrust into a heavy leadership position, relying on his quick thinking to protect his vulnerable sibling.

Abby is a six-year-old girl who copes with partial paralysis in her legs following a playground accident at age two. She uses a walker to move and crawls when necessary, as her parents actively resist utilizing a wheelchair to force her to build leg strength. Though she displays typical six-year-old behavior—particularly a strong aversion to water—she proves adaptable when thrust into an outdoor emergency.

Moose is a golden retriever whom Jonathan selected from an animal shelter years prior. Highly obedient and perceptive, Moose serves as a steadying presence for the children in the woods. He senses environmental changes before the humans do, offering warning barks before danger arrives.

Mr. Palmer is the determined father of Jonathan and Abby. He deeply loves his family and actively encourages Abby to build her physical strength. When he separates from the children to seek medical help for his wife's injury, he finds himself cut off from Magpie Island and forced to problem-solve his way back to his kids.

Mrs. Palmer is an outdoors enthusiast who refuses to let her daughter's physical condition stop the family from enjoying camping trips. She maintains high standards for her children, promoting healthy eating and physical independence. Her sudden ankle injury serves as the catalyst that separates the family just before the earthquake hits.

Kenny is a young man living in the town of Beaverville who steps up to help others during the crisis. He possesses a chainsaw and offers hands-on assistance to stranded travelers trying to travel the tree-blocked roads following the natural disaster.