Jonah is a thirteen-year-old teenager who enjoys a comfortable life in his adoptive family. He actively avoids worrying about his origins until he receives an anonymous letter in the mail stating he is one of the missing. Though he wants to ignore the strange occurrences surrounding his adoption file, his best friend's sudden crisis forces him to investigate. He protects those he cares about, even when faced with frightening events.

Chip is Jonah's new best friend who recently discovers he is adopted after finding a hidden birth certificate. Unlike Jonah, Chip channels his feelings of betrayal into an obsessive quest to uncover his true identity. He acts as an emotional catalyst for the investigation when he also begins receiving vaguely threatening letters at both his new and old addresses.

Katherine is Jonah's biological sister within his adoptive family. She is a confident and loyal sibling who thinks quickly under pressure. Though she initially clashes with Jonah like a typical younger sister, she proves to be an invaluable ally who faces frightening situations head-on to help solve the mystery.

Grant Hodge is a short, enthusiastic man with wiry hair who operates under the guise of an adoption group leader. He harbors hidden motives concerning the children from the mysterious plane. He works alongside his partner to execute a secretive plan involving a remote cave.

Gary is the bulky, intimidating partner of Grant Hodge at the adoption conference. He acts as the muscle of their operation, ruthlessly enforcing their hidden agenda. He deals physically with anyone who attempts to thwart their plans for the adopted teenagers.

Angela is a former airline worker who witnessed an impossible event thirteen years ago involving a plane populated by thirty-six infants. Her refusal to stay quiet about what she saw led to her dismissal by government officials. She serves as a crucial link to the past with a cautious nature regarding modern technology and communication.

JB is a mysterious individual who appears in unexpected places to offer cryptic warnings to Jonah. He is deeply entangled in the secrets surrounding the missing children and operates with an enigmatic agenda. He knows far more about Jonah's origins than he reveals and warns the children about the dangers of written records.

James Reardon is an intimidating FBI operative associated with both Jonah and Chip's adoption files. He possesses a smooth, silky voice that quickly turns threatening when pushed for information. His actions indicate he is involved in a larger government cover-up regarding the children's origins.

Jonah's adoptive mother is deeply loving and protective of both her children. She views Jonah's arrival in their lives as a miracle and strives to maintain an open dialogue about his adoption. She often experiences anxiety when her children ask difficult questions about their past.

Jonah's adoptive father is a fiercely protective parent who refuses to be intimidated by authority figures. He actively pushes back against James Reardon's veiled threats during their office meeting to ensure his son's safety. He fights for Jonah's right to uncover the truth about his past.

Chip's adoptive father is a secretive man who kept his son's adoption hidden for thirteen years. His firm refusal to discuss the adoption acts as the trigger for Chip's obsessive search for his true identity.

Daniella is another adopted thirteen-year-old whose name appears on a mysterious list of survivors alongside Jonah and Chip. Her sudden and unexplained move to a new city deepens the mystery. Her absence at a later conference raises alarms for the investigating friends.