Frances is a 52-year-old romance novelist whose career is currently faltering following a harsh critical review and a rejected manuscript. She arrives at the boutique health resort hoping to fix her life after falling victim to an internet romance scam. She maintains a cynical but outwardly cooperative attitude toward the retreat's strict rules, using humor to deflect her insecurities about aging and her declining career.

Masha is the mysterious director and creator of Tranquillum House. After surviving a near-fatal heart attack, the Russian immigrant abandoned her high-powered corporate career to reinvent herself as a health guru. She maintains an ethereal, otherworldly presence that commands absolute obedience, enforcing mandatory fasting and a vow of silence to push her guests out of their comfort zones.

Jessica is a young woman who recently won a $22 million lottery jackpot alongside her husband. The sudden influx of wealth triggered a profound identity crisis, leading her to pursue multiple cosmetic surgeries to match the aesthetics of wealthy social media influencers. She books the couples retreat in a desperate attempt to save her deteriorating marriage.

Heather is a medical midwife and a grieving mother stuck in deep depression following the death of her son three years ago. She openly resents the arbitrary rules of Tranquillum House, particularly questioning the logic behind the mandatory five-day silence. Her medical background makes her highly suspicious of Masha's unscientific approach to healing.

Yao serves as a personal wellness consultant at Tranquillum House. A former paramedic, he abandoned his medical career following a depressive episode to follow Masha into the wellness industry. He acts as the primary enforcer of the retreat's strict protocols, conducting daily blood tests and confiscating contraband from the arriving guests.

Tony is a retired professional Australian Rules football player dealing with physical decline, a recent medical scare, and social isolation. Mourning the death of his beloved dog Banjo, he feels completely out of place at the wellness center. He struggles with the physical demands of the retreat, finding himself easily exhausted by minor exercise and frustrated by the enforced quiet.

Ben is a former mechanic who won the lottery with his wife. Uncomfortable with his sudden wealth, he finds his only joy in his brightly colored sportscar. He views the wellness retreat as an unnecessary indulgence but attends solely to appease his wife's anxieties about their relationship.

Carmel is a former corporate worker and single mother of four daughters. Since her husband left her for a younger woman, she suffers from extremely low self-esteem. She fully embraces the spa's strict dietary rules, hoping dramatic weight loss will make her ex-husband regret his departure.

Lars is a successful gay divorce lawyer who frequently attends high-end health spas. He utilizes these retreats to disconnect from his demanding career and personal life. He currently uses the silence of Tranquillum House to avoid discussing surrogacy and parenthood with his partner.

Napoleon is an extroverted schoolteacher working tirelessly to keep his family intact after a tragic loss. Unlike his cynical wife, he embraces the spa's daily schedule, willingly participating in early morning tai chi. He uses forced optimism to mask his own profound sorrow over his son's death.

Zoe is a twenty-year-old college student marking the third anniversary of her twin brother's death. She attends the retreat out of a sense of obligation to her overprotective parents. She manages to smuggle wine into the facility specifically to toast her brother's upcoming birthday.

Zach is the deceased son of Heather and Napoleon and the twin brother of Zoe. His death by suicide three years prior serves as the central trauma fracturing the Marconi family. His memory dominates his parents' thoughts, creating a heavy burden of guilt they carry into the retreat.

Delilah is a wellness consultant and former personal assistant at Tranquillum House. She carries out the facility's strict protocols but secretly views her employer as deeply narcissistic. She treats the developing tension among the guests as a source of mild entertainment.

Paul is the online persona used by an internet scammer to steal money from Frances. Presenting himself as an American widower, he courted Frances for six months before faking a medical emergency involving his son to extract funds.

Ari is the fictional son invented by the online scammer who targeted Frances. Although he does not actually exist, Frances developed genuine maternal feelings for the boy, making his sudden disappearance deeply painful.

Lucy is Ben's sister who battles severe substance addiction. She frequently demands financial support from Ben and Jessica, causing significant friction in their marriage as she exhausts the couple's resources.

Ray is Lars's partner who stayed behind while Lars visits the wellness center. He actively pushes for the couple to have a child using his own sister as a surrogate, creating ongoing tension in the relationship.

Joel is Carmel's ex-husband. He left his family to marry a younger woman, a rejection that fundamentally shattered Carmel's confidence and drove her to seek physical transformation at the wellness center.

Jan is a massage therapist employed at Tranquillum House. A divorced woman recently dating a police officer, she projects the intimidating demeanor of a prison guard and shows little enthusiasm for the spa's overarching ethos.

Gus is a police officer and Jan's new romantic interest. He operates outside the closed environment of the wellness center.