The story of "Variant Hydra" begins in a secret biological genetic laboratory. The female researcher escaped from the laboratory with the gene sequence of the Hydra and cultivated the monster Hydra in a virgin forest in Mingling Mountain! In order to obtain No. 9 growth hormone, she used the scales of the Hydra to set a trap, which attracted Professor Chen and her fiancé. Professor Chen and his party who did not know the truth fell into one trap after another! The biggest highlight of the film is that the plot is constantly reversed. Everyone who walks into the virgin forest hides their true purpose. The forces of justice and evil confront each other, and a killing begins! Hydra seems to be the protagonist of the film, but it has become a murder tool for sinister people. Two people who used to love each other have become the biggest enemy because of different life pursuits! And between Professor Chen and the heroine's fiance, Xiaobai, there were also various suspicions. Who stole the No. 9 growth hormone, and who was lurking in the team and led everyone into a puzzle step by step?