Gu Changhe, the son of a silent and resolute detective, met Lin Wanqing, a girl with a voice as clear as the Songhua River.
A silent secret love that runs through the entire youth, quietly takes root under the umbrella on rainy nights, and is silently hidden at the fork in the road of the college entrance examination.
He chose to become the guardian of the Songhua River, dedicated his life to the dangerous criminal investigation front, and locked his deep feelings into a diary written for twenty-six years. She flew to a wider world, experienced prosperity, marriage and awakening, and re-examined her past after a divorce in middle age.
Until he died in the line of duty, the diary that had never been shown was revealed - every page was filled with "I love you" that had never been spoken.
Spanning thirty years, people from the two worlds finally meet in the truth: some love never begins, but continues throughout; some protection, without asking for response, has become life itself.
This is the story of a long river of silence and a gorgeous sunset.
About choices, about regrets, about those unspoken deep feelings that illuminate each other's lives.
Concept: Is unspoken love considered true love? Is a guardianship that is unknown to it valuable? Is it still meaningful to understand it after so many years?