Saw IV opens with John Kramer's naked corpse lying on an autopsy table. Just in case there was any doubt that he really did die at the end of Saw III, the film spends a lot of time with his dead body as it's dissected. Piece by piece, Jigsaw's body is taken apart. But the games aren't over yet. Not by a long shot.
Like Saw III, Saw IV is better than I remembered, but it's also massively flawed, like all the Saw movies. The first trap in Saw IV is utterly nonsensical: two men are chained together, their chains attached to a crank. One man has his eyes sewn shut, the other his mouth. Soon, the crank begins to turn, and apparently both of them perish. There's no handy tape to explain to us who these men are, or what they did to deserve their predicament. It's very, very gory, and very, very badly edited. All of the Saw films are fond of the rapidfire, epilepsy-inducing montages, but Saw IV is actively difficult to watch because of the nauseating way the camera moves. The colours look even more exaggerated, too, to the point where some scenes almost look like they're in greyscale. Bleurghhh.
It takes a little while for Saw IV's characters to emerge. Once again the police aren't just investigating the murders, they're actively involved. The only cop left from the original investigation, Rigg, is at the heart of this movie: because everyone around him has been murdered, he's become obsessed with the case, to the point that it's destroying his personal relationships. Unfortunately, because he's the only one left, he's also the prime suspect. FBI agents Strahm and Perez have been brought in to investigate, and the complexity of some of Saw III's traps has tipped them off to the existence of a second accomplice. Someone else was helping Jigsaw, and all the signs point to Rigg. When he discovers that Detective Matthews is still alive (while poor Kerry isn't!) Rigg has to submit to Jigsaw's tests to save him ... but unfortunately for Matthews, the lesson Jigsaw wants to teach Rigg is that it's impossible to save everyone.
Saw IV sits kind of strangely alongside Saw III. In III, Jeff had to put aside his personal grudges to save the lives of some pretty terrible people. In IV, Rigg must set aside his personal saviour complex to allow people to try to save themselves - or, if they can't, he needs to learn to let them die, and accept that he can't save everyone. Rigg has to actually put some people into their traps, though, and the film flirts with the idea of setting him up as Jigsaw's accomplice - though we've already seen that Jigsaw often uses people to do the physical labour that he can't manage, and has done ever since he made Zep in the first movie kidnap Dr Gordon's wife and child. (Actually, that might make the whole idea of a second accomplice nonsensical, because there will always be someone Jigsaw can coerce into doing his bidding, even if they aren't wannabes like Amanda -- but there is a second accomplice, so let's not think too hard about that.)
Ultimately, just like virtually everyone else before him, Rigg will fail his test and doom various other people to death in the process. What's more interesting about Saw IV, though, is the sizeable chunk of Jigsaw backstory it offers us. For one thing: Jigsaw had a wife. He nearly had a child, too, before a drug addict accidentally caused his wife to miscarry, and set in motion the whole Saw thing. That addict, Cecil, was the first person to be tested by a Jigsaw trap, the first time John had used his engineering skills to create torture devices. The origin of the pig head mask is also explained (though it's ... still kinda random) as well as the origin of the Billy doll. Everything that had previously been a mystery (or just a cool image without any explanation) gets explained in Saw IV, and unlike the awkward, stupid backstories that later sequels offered horror movie villains like Freddy and Jason, Jigsaw's backstory resonates. He's a very human kind of monster, and while much of his philosophising doesn't really hold water, it does make sense to him. His motivations suddenly come into focus; he's actually a cohesive character. This feels like a significant revelation, somehow.
Saw IV is the first Saw movie not to be written by Leigh Whannell (though it is still directed by Darren Lyn Bousman, which explains why it looks terrible) and it seems like the new writing team really has a handle on this stuff. It'll be interesting to see what they do with the Hoffman character over the next couple of movies, and whether they can create a more worthy successor to Jigsaw than Amanda turned out to be.