The Seventh Day Underwater

August 17th. On the same day twenty-two years ago, Shen Du's mother disappeared by the river, and her body was never found. As a water conservancy engineer, Shen Du saw a face turned white from the surveillance screen during routine underwater surveying - his mother Lin Xiulan, wearing the red dress from the day she disappeared, looking at him across the turbid river water. What sent shivers down his spine was: three meters behind his mother stood a young man who looked exactly like him, with the dark gray braided rope his mother left for him wrapped around his right wrist. He went through all the files and found that on the afternoon of August 17, twenty-two years ago, the entire river stood still for seven minutes. There was no wind, no waves, and all the hydrological instruments returned to zero - in those seven minutes, the river surface turned into a mirror. In the early morning of the next day, Shen Du found a notebook soaked in water in the ruins of the old hydrological station. On the title page is written a line of slanted handwriting written by a seven-year-old child: "My name is Shen Nian. I have lived underwater for twenty-two years. My mother fished me out of the water and pushed me back. Now it's your turn." The braid around his wrist was hot. Tomorrow is August 17th. He must decide who should stay on the shore before the next "seven minutes of stillness" arrives - him or the other self who has been waiting underwater for twenty-two years.