In 2035, Ran Lin, a police officer in Time Administration, time travels back to 2015, the year of his father got killed in front of him. He lost his father at age of nine, and ever since then there was not a day he could not think of his father and his death, even age grew and memories became blur. His father passed him a locked wood box at his final time. He got a feeling that his father’s murder is related to himself, and the answer might be found in that box. But Ran couldn’t get enough courage to open the box and face with the truth. The position in Time Administration provides him a chance to time travel. Ran understood the consequences of changing history, but he yearned for seeing his father again. He broke the rule and tailed after his dad and young himself. The more time he followed, the stronger feeling came to his mind that there was a man look likes him in his childhood memory, and father acted like he already knew everything. At very last, Ran successfully stopped the kidnap of his young self and protected his father’s research out of criminal’s hand, but still couldn’t protect his father from a fatal shot. By the bedside, father passed him a key to the box before he closed eyes.