According to the information on Zhihu's website, the story background of Chainsaw 9: Vortex was set many years after Jigsaw's death, and Jigsaw was not mentioned much. This time it is a direct declaration of war. The murderer behind the scenes played with the police in applause. Then, several policemen who made false cases were punished by him one by one and sentenced to death. So I can't catch up with the plot because the plot of Chainsaw 9: Vortex is not closely related to the previous work.