A mysterious entity that can mimic others to evade capture and confound investigators. Its origins are unknown, but it possesses a very physical, albeit unfamiliar, form.

A well-liked Little League coach wrongly accused of a heinous crime. His case is central to the story's moral and investigative dilemmas.

An eccentric yet brilliant detective known for her meticulous investigative skills. She has a background from previous cases in the Mr. Mercedes series and plays a key role in the investigation.

A young district attorney with an Alfalfa-like cowlick who initially believes firmly in the accused's guilt. As the case evolves, he reassesses his initial confidence.

An adolescent dealing with the traumatic aftermath of his brother’s murder. He tries to maintain control amidst family tragedy and loss.

A disreputable and disgruntled officer who faces significant personal and professional challenges during the investigation. He is manipulated due to his various weaknesses.

Ralph’s supportive wife who contributes valuable perspectives, suggesting unconventional explanations for the evidence.