After losing her husband in a tragic traffic accident, Lee Shin-ae (Jeon Do-yeon) relocates to Miryang, located in South Gyeongsang Province, which is her late husband's hometown, alongside her son Jun. Their journey to a fresh start takes a turbulent turn when Shin-ae's car breaks down upon entering the town. Fortunately, local mechanic Kim Jong-chan (Song Kang-ho) comes to her aid, not only fixing her car but also supporting her as she opens a new piano school and seeks to buy land to build a home. Jong-chan presents himself as a mere Good Samaritan, but his presence is significant.
One day, Shin-ae encounters a middle-school girl, referred to as "the girl," whose father is Park Do-seop, Jun's daycare teacher. The encounter becomes more complex when a pharmacist suggests that faith in God could solve Shin-ae's struggles. Although skeptical, she accepts the pharmacist's scriptures. At home, she and Jun share a playful moment filled with laughter, but shadows linger as her brother visits from Seoul. He questions her decision to return to Miryang, especially given her husband's betrayal, but Shin-ae denies any infidelity while grappling with unresolved feelings towards her late husband.
A harrowing twist unfolds when one night, after a late outing, Shin-ae discovers Jun is missing. A chilling phone call—likely from Jun's abductor—forces her to withdraw all her savings for a ransom, only to reveal her deception regarding her financial status when it all becomes too little. Upon returning home devastated, she finds the girl outside her residence, but the girl swiftly flees. The tragedy deepens when police inform Shin-ae that Jun has drowned at a reservoir, and the culprit turns out to be none other than Park Do-seop. In a shocking display of emotions, Shin-ae attends Jun's funeral without shedding a tear, caught in a web of grief and disbelief.
Feeling utterly lost, Shin-ae approaches the pharmacist again, who persuades her to explore faith, despite lingering questions about the goodness of God allowing such tragedy. With Jong-chan by her side, Shin-ae embraces this newfound belief, seeking inner solace. This new faith leads her to unexpected encounters with Jun's past, including the girl who had once been bullied at daycare.
During a thoughtful birthday celebration organized by her church friends, Shin-ae resolves to visit Do-seop in prison to offer him forgiveness. Jong-chan accompanies her, though he struggles to comprehend her need for this closure. Their visit reveals a shocking twist: Do-seop, now a believer, claims his sins have been forgiven. Confusion floods Shin-ae—how can someone else receive absolution before she does?
Amidst these emotional upheavals, Shin-ae's actions take a darker turn as she grapples with her turmoil. A theft of a CD from a store and an ill-fated romantic encounter leave her spiraling, culminating in a self-destructive act. During her recovery, Jong-chan supports her, steering her towards healing and renewal as they navigate the complexities of their intertwined lives. As Shin-ae wrestles with her grief and her past choices, the road to redemption remains fraught with challenges, but a glimmer of hope persists.
