Art is a 12-year-old boy suffering from dissociative amnesia after a traumatic event. With shaggy blond hair and green eyes, he wears a blue jacket with the name "Arthur" on the tag, which serves as his only initial link to his identity. Though quiet and uncertain as he struggles with his memory loss, he possesses a surprisingly deep knowledge of fine art and demonstrates sharp resourcefulness when pushed into danger.

Camille is Mary's 10-year-old daughter, recognizable by her vibrant red hair and boundless energy. She is highly talkative and fiercely independent, providing a sharp contrast to Art's quiet demeanor. She takes her promise to watch over Art seriously and proves to be a brave, quick-witted companion when they face unexpected threats.

Dorchek Palmer is a 28-year-old tech millionaire who made his fortune developing gaming apps. After achieving massive financial success early in life, he seeks extreme thrills by orchestrating a high-stakes art forgery scheme. Youthful in appearance and easily overlooked, he commands a team of skilled operatives and relies heavily on surveillance technology to track his targets.

Mary is a senior book editor and an experienced foster parent who keeps her dark hair pulled back in a neat bun. She handles emergency placements with practiced patience and provides temporary care for children in crisis. As an independent single mother, she creates a loving, supportive environment for both her daughter and the children she takes in.

Detective Evans is the lead police investigator assigned to Art's case. She is a highly observant investigator who keeps her glasses hanging from a chain around her neck. She recognizes the honesty in Art's amnesia claims and promises to help him uncover his identity.

Arthur Hamilton Sr. is a highly respected art authenticator and Art's father. Hired by the National Gallery of Art to verify the authenticity of a newly acquired masterpiece, his meticulous attention to detail uncovers dangerous secrets. He is a dedicated parent who actively shares his passion for history and art with his son.

Dr. Belette is the Director of Acquisitions at the National Gallery of Art. An older man who favors tweed jackets, he handles the museum's high-stakes art purchases. He maintains a hidden alliance with Dorchek Palmer, using his institutional authority to facilitate the forgery scheme from the inside.

Regina Cash is a highly trained operative working on Dorchek Palmer's team. She uses disguises and tactical equipment, including tranquilizer darts, to surveil and corner targets on city streets.

Eric McClain operates as a physical enforcer for Palmer's crew. Armed with tranquilizer darts, he relentlessly chases Art and Camille through hotel lobbies and crowded areas, though his overconfidence often results in embarrassing failures.

Winston Lantham is Palmer's designated "roper," a manipulative operative skilled at gaining targets' trust. He uses false credentials and preys on the children's desire for safety to force them into Palmer's custody.

Nigel Stenhouse is the last active field agent on Palmer's pursuit team. He utilizes a thick British accent and clever social engineering to extract information from civilians while tracking the children.

Bazanov operates as a driver and physical muscle for Palmer's crew. He handles the logistical aspects of transporting kidnapped targets but proves ill-prepared for the chaotic resistance put up by his young captives.

Victor Baudin is a masterful art forger who views himself as a modern alchemist. Utilizing traditional pigments, aged canvases, and exotic materials, he meticulously crafts indistinguishable fake paintings for anonymous clients.

Detective Wasberger is a police officer who inadvertently falls for Palmer's sophisticated disguise. Believing Palmer is Art's concerned older brother, he hands over critical contact information that puts the children directly in danger.

Elizabeth Downing is the director of the National Gallery of Art. She oversees the museum's high-profile acquisitions and relies on the expertise of her staff to safeguard the institution's financial and cultural reputation.

Kim Yoon is the executive assistant to the National Gallery's director. Accustomed to dealing with wealthy socialites and politicians, she expertly manages the logistical demands of the museum's elite board members.

Damon Sacks is the fictional US Secretary of State and a stringent member of the National Gallery of Art's board of trustees. He represents the high-level government oversight involved in the museum's multi-million-dollar acquisitions.

James Appleton is the fussy manager of the Hotel Monaco. He is more concerned with the decorum of his establishment and the property damage caused by unruly children than the actual peril unfolding in his lobby.

Aunt Judy is Mary's sister. She provides a vital support system for the Sullivan family, stepping in to watch Camille or stay at Mary's house during emergencies to ensure the home is covered.