So-nyo is the 69-year-old matriarch of a rural South Korean family who goes missing in Seoul. Unbeknownst to her children, she suffers from severe headaches and memory loss. She spent her life tirelessly cooking, farming, and sacrificing her own needs to ensure her family's survival. Her sudden disappearance makes her children and husband confront how little they truly know about her inner life.

So-nyo's unnamed husband is an elderly man who lives in the rural town of Chongup. Throughout their marriage, he frequently left home for months at a time to travel or pursue other interests, returning only when he needed his wife's care. Accustomed to walking quickly ahead of her in public, his lifelong habit of ignoring her physical discomfort becomes a source of immense guilt during the search.

Chi-hon is So-nyo's eldest daughter, a successful and independent novelist who frequently travels for work. She often grew easily frustrated with her mother's rural sensibilities and lacked patience for their phone calls. Following the disappearance, she questions her past behavior, realizing she viewed So-nyo merely as a mother figure rather than an individual woman.

Hyong-chol is So-nyo's eldest son, who works as a marketing director selling units for an apartment development company. As a young man, he promised to become a prosecutor and provide a comfortable life for his mother. Though he achieved corporate success, he failed to keep this specific promise, leaving him burdened by heavy expectations and unspoken regrets.

The unnamed youngest daughter is a highly educated woman who attended a top university in Seoul. Despite her academic promise, she chose to become a stay-at-home mother to three children, a decision that shocked her mother. She struggles to balance her current domestic responsibilities with her desire to help search the city.

Eun-gyu Lee is a man from So-nyo's past who became a quiet, steadfast presence in her life. They met in the country when she was a younger woman, and he provided emotional support outside the awareness of her husband and children.

So-nyo's unnamed sister-in-law is a hardened woman who lost her own husband in a fire at a young age. She frequently treated So-nyo harshly, acting more like a strict superior than a peer. With So-nyo missing, she faces her own deep regrets about her past criticisms.

Kyun is So-nyo's husband's deceased younger brother. Bright and eager for an education, he shared a close bond with So-nyo and helped her with household chores. His sudden and tragic death deeply affected the family and became a source of ongoing pain.

Tae-hee Hong is a young woman who works at the Hope House orphanage. She reveals a hidden side of So-nyo's routine to the family, explaining how the elderly woman regularly visited the facility to clean and donate money.

Yu-bin is Chi-hon's boyfriend. He attempts to offer companionship and distraction as Chi-hon struggles with her mother's disappearance, eventually suggesting a trip abroad to help her cope with the stress.