He received a love letter from 86 years ago, signed "The Widow".
Lin Shen never thought that the "time" he had devoted so much effort to research would materialize in such a cruel way - the laboratory instruments began to receive distress signals from Nanjing in 1937. The source of the signal was a female student named Ye Zhiqiu.
Through the intermittent "time gaps", he witnessed everything about her: her perseverance in the flames of war, the glimmer of light in desperate situations, and her eyes with desperate hope when looking towards the future. He couldn't help but want to save her, even if the cost was violating the iron laws of time and space.
However, the "echoes" across time and space have led to deeper mysteries: the mysterious disappearance of their parents, the secrets guarded by the family, a "watchman" who claims to be their future descendants... All clues point to a cold truth: their encounter was not accidental, but a cruel closed loop of love and sacrifice that had been laid out long ago.
When salvation becomes the beginning of destruction, when deep love becomes the source of paradox, can they find a third way in the cracks in time?
