Liu Xuan (Deng Chao), a self-made tycoon, has just bought a piece of land and teamed up with strong woman Li Ruolan (Zhang Yuqi) to use terrifying sonar technology to drive away fish for land reclamation. The mermaids have long lived in the sea in the nearby area. In order to survive, the leader, Octopus Bage (Show Luo), sent the mermaid Shanshan (Lin Yun) to "seduce" Liu Xuan and prepare to assassinate him. Unexpectedly, Shanshan secretly fell in love with Liu Xuan during the undercover process and repeatedly disrupted the assassination plan, while Li Ruolan was preparing a more crazy and evil plan...