Saw IV

A police detective is forced to participate in a series of deadly traps after the apparent death of the Jigsaw Killer, only to discover that the killer's mechanisms have been set in motion by a new accomplice. As officers investigate the crime scenes, a gruesome video testament left by Jigsaw gradually reveals his origins and motivations. The film interweaves past and present, suggesting that the traps were designed long before anyone realised, and culminates in a twist that recontextualises the timeline of the entire series.