In the film's second act, Geum-ja tracks down Mr. Baek and incapacitates him. Upon capturing him, she discovers a collection of mobile phone charms depicting cartoon characters attached to Baek’s cell phone. She realizes these belong to multiple children. Baek is not merely her personal oppressor, but a serial killer who kidnapped, ransomed, and murdered four other young children, using the extortion money to buy luxury items.
Recognizing that her single vengeance is insufficient, Geum-ja contacts the parents of all four deceased children. She gathers them in an abandoned schoolhouse, shows them Baek's recorded snuff videos, and holds a vote on whether to hand him to the police or execute him themselves. The parents vote unanimously for execution. Wearing plastic raincoats to protect their clothes, each parent takes turns entering the room to torture and stab Baek until he dies.
After burying Baek's body in the snow, the parents meet at Geum-ja's bakery, eat cake together, and divide the remaining ransom money retrieved from Baek's bank account. Later, Geum-ja is visited by a vision of Won-mo, who appears as an adult. Instead of forgiving her, his ghost inserts a gag into her mouth, signifying that her revenge has not earned his absolution.
In the final scene, Geum-ja bakes a pure white cake. She carries it out into the falling snow to Jenny, who offers her a piece and tells her to "live white". Overwhelmed by grief, Geum-ja plunges her face directly into the white cake, sobbing uncontrollably in the snow as the narrator notes that she was never able to achieve the purity she sought.