The story takes place in the mysterious and unpredictable blue sea. Kate (Halle Berry) is a senior diver with the title of "Shark Whisperer". After nearly ten years in the industry, she has not only gained wide recognition in the industry, but also owned her beloved fishing boat, the Volante, through her own hard work. An accident caused Kate to lose almost everything, including her partner who trusted her deeply. The huge blow made Kate unable to recover. She refused to dive into the sea again and was immersed in sadness and regret all day. Kate's depression directly affected her life, and the increasing debt would eventually make her lose the Volante. With the help of her good friend Jeff (Olivier Martinez), Kate decided to return to her post with a businessman. This time, she was going to challenge the dangerous area that all divers were afraid of - Shark Harbor.