No matter how old you get, life is just a 'dark history generator'?

Hae-su works at a factory on the outskirts of Seoul. Returning home from work, she makes a phone call that goes to voicemail; nearing her residence, another phone call comes in, but she doesn't pick up. Inside the house is her mother's body—she died from mysterious circumstances. A knock on the door goes unanswered, but when a plainclothes police officer arrives, Hae-su lets him in. An exchange of documents, uncertain glances. With Hae-su and her tempermental brother the only attendants at her mother's funeral, there are more questions than answers.