The winter after Yuran's passing is bitterly cold. Jeongsuk tracks down Changheon, the young man who stayed by Yuran's side until the very end. Jeongsuk cannot bear it – not without knowing why Yuran left without a word to her, when the two of them had been everything to each other. But all Changheon carries is the memory of one brief, tender winter: the winter he called Yuran by a word he had never spoken aloud before — “Mom." Jeongsuk and Changheon come face to face with each other's loss. On a night when not a single photograph of Yuran remains, each of them asks again what she meant by the word she left behind: “us.”