Cheng Yu, a 29-year-old marine photography assistant, encountered a yacht running aground while returning from an offshore shooting. He was trapped on a tropical island with emergency nurse Su He, swimming coach Zhou Cen and yacht owner Luo Jing. Rescue signals are intermittent, fresh water is limited, and low tides reveal different black reef ridges every day. The path that was possible yesterday may be completely cut off by wind and waves the next day. Cheng Yu could only rely on the incomplete tide table, the color of the reef, the direction of seabirds' return and limited equipment to judge the route, allocate water sources, move camp and strive for a window for help. However, he is accustomed to verifying things alone before telling others. This seemingly prudent habit soon causes his companions to pay the price of injury. To take three strangers away together before the rescue window closes, he must learn not only to understand the sea, but also to hand over uncertainty, risk and choice to everyone in a timely manner.
