Stephanie is a widowed mother living in Warfield, Connecticut. She runs a popular motherhood blog where she shares advice and seeks connection with other women, a project she started to combat her own isolation after her husband's death. She relies heavily on her friendship with Emily, though she often feels inadequate compared to Emily's glamorous lifestyle. She is highly involved in her son's daily routine and feels a strong pressure to meet the societal expectations of modern motherhood.

Emily is an elegant, sophisticated woman who commutes to Manhattan to work in publicity for a famous fashion designer. She stands out among the local parents with her custom Italian perfume, designer clothing, and unapologetically confident demeanor. She vanishes suddenly after asking Stephanie to watch her son for the afternoon, setting off a police investigation and leaving her family in turmoil.

Sean is Emily's British husband who works on Wall Street. Initially presented through Emily's complaints as a distant husband who works long hours, he returns home to deal directly with the crisis of her disappearance. He struggles to manage his young son's distress and coordinate with the ongoing police search while adjusting to his suddenly empty house.

Nicky is Emily and Sean's five-year-old son. He is best friends with Stephanie's son, Miles, which initially brings their mothers together. Following his mother's sudden absence, he experiences severe anxiety and begins displaying angry, disruptive behavioral changes.

Isaac is an investigator for Allied Insurance Company, which holds a massive policy issued through Sean's employer. He is tasked with investigating the unusual circumstances surrounding Emily's disappearance. He brings external scrutiny to the families in Connecticut just as they are attempting to establish a new normal.

Miles is Stephanie's five-year-old son. He lost his father at a young age, leading his mother to center her entire life around his schedule. He provides gentle emotional support for Nicky during the confusion of Emily's disappearance.

Davis is Stephanie's late husband who died in a fatal car crash prior to the main events of the story. He moved the family from New York City to Warfield and worked from home while restoring their house. His death left Stephanie as a single mother.

Chris is Stephanie's half-brother, who grew up in Wisconsin as part of their father's secret second family. He dies in the same car crash as Davis, leaving a lasting and complicated emotional impact on Stephanie's adult life.

Dennis is a famous fashion designer who employs Emily in his demanding publicity department. Following her disappearance, he utilizes his celebrity status to appear in the media and draw public attention to the ongoing search.

Bernice is the caretaker for Emily's mother, who suffers from dementia. She works at the Michigan residence and provides background information about the family's history when Stephanie comes looking for answers.