Juno is a 67-year-old former therapist living with severe lupus. Following a professional scandal involving an inappropriate relationship with a client, she lost her career, her husband, and her home. To escape the streets, she secretly moves into the crawl space of the Crouch family's house. She spends her days observing the family, eating their food, and eventually using their computer to investigate their private lives.

Winnie is a Seattle mother fiercely dedicated to presenting a flawless image to her upper-middle-class neighbors. She micromanages her household, insisting on organic vegetables, a specific doorbell chime, and a highly controlled environment for her son. Beneath this polished exterior, she struggles with depression, a strained marriage, and heavy guilt over a secret incident from her past work at an organization called Illuminations.

Nigel is Winnie's husband, a man worn down by the heavy secrets he shares with his wife. The resulting strain on his marriage leads him to sleep in the den and keep a hidden stash of Jack Daniels in the house. Frustrated by Winnie's inability to move past their shared history, he begins seeking emotional intimacy outside of his home.

Samuel, who prefers to be called Sam, is Winnie and Nigel's teenage son. He feels smothered by his mother's overbearing rules and acutely senses the unspoken tension between his parents. Seeking an escape from his restrictive home life, he secretly eats forbidden sugary foods like Froot Loops, steals painkillers from his parents' bathroom, and harbors a deep suspicion that he might be adopted.

Dakota is Winnie's twin brother. He struggles with severe alcohol use, gambling issues, and schizophrenia. After his wife throws him out, he moves into the Crouch household. His volatile presence and unrefined habits clash violently with Winnie's desperate need to maintain a perfect domestic image.

Josalyn is an 18-year-old runaway who lived in a tent and struggled with substance use and bipolar disorder. As a pregnant teenager, she became a client of Winnie's at the Illuminations organization. Her past interactions with Winnie form the basis of the secrets currently haunting the Crouch household.

Terry is Josalyn's mother. She becomes unexpectedly drawn into the lives of the Crouch family when Juno contacts her with disturbing information regarding the past. She arrives at the house in Seattle demanding answers about her family.

Manda is Dakota's wife. Exhausted by his destructive behavior, gambling, and drinking, she forces him out of their shared home, which sets off the chain of events leading him to stay with the Crouches.

Dulce is a coworker of Nigel Crouch. She shares intimate lunches with him at a restaurant called Palomino, engaging in an emotional affair that threatens to push his already fragile marriage to the breaking point.

Shelly is Winnie and Dakota's older sister. She firmly believes in sharing the burden of their troubled brother, pressuring Winnie to open her pristine home to him when his wife kicks him out.

Kregger is Juno's ex-husband. He left her and took his two sons from a previous marriage with him after Juno was sent to prison for professional misconduct as a therapist.

Joe is an unhoused man who knows Juno from the time she spent living in the public park. He pays attention to her movements and briefly follows her, questioning what she is up to when she approaches the Crouch residence.