The film continues the story of the Jigsaw Killer's obsession with teaching people the value of their lives. Despite Jigsaw's death in the previous installment, the film focuses on his ability to manipulate people into continuing his work. The story follows Lieutenant Daniel Rigg being put through a series of tests in order to try to let go of his obsession with saving everyone, whilst at the same time attempting to save his partner.
The film was released in North America on October 26, 2007 to generally negative reviews from critics. Despite this, the film was a box office success, grossing $139 million worldwide. It was followed by Saw V on October 24, 2008.
A wax-coated microcassette is found in John Kramer's stomach during his autopsy. It reveals to Mark Hoffman, the detective called in to hear it, that the games, including his own, will continue. Elsewhere, two men - one with his eyes sewn shut, the other has his mouth sewn shut - awaken in a mausoleum, chained at the neck to a winch. The blinded man panics and activates the winch while attacking the muted man, who kills him and removes a key from his collar to free himself.
Four days after Allison Kerry's death, a SWAT team led by Hoffman and Lieutenant Daniel Rigg finds her body, and Hoffman warns Rigg for breaking through an unsecured door to reach her. The scene is also investigated by Peter Strahm and Lindsey Perez, Kerry's FBI contacts, who received a message and a key from her. Noting Kramer's and Amanda Young's physical limitations, Strahm states they are looking for an unidentified accomplice; he soon becomes suspicious of Rigg, who has developed an obsession with saving people in the six months since the disappearance of detective Eric Matthews. That night, Rigg is attacked in his home; he awakens to learn that Matthews is alive and has ninety minutes to save himself, with Hoffman's life also at risk. Meanwhile, he must play his own game to face and overcome his obsession. The detectives are shown to be at each end of a large seesaw: Matthews is held atop an ice block by a chain-noose, and Hoffman is strapped to a chair with electrodes at his feet. If Matthews slips or too much ice melts, both men will die. A man later arrives to oversee the game.
Rigg finds a prostitute, Brenda, bound to a chair in his living room, which he accidentally turns on the trap, which slowly tears apart her scalp. Rigg frees her, but kills Brenda in self-defense when she attacks Rigg with a knife. Rigg is then led to a motel and instructed to abduct the owner, Ivan Landsness, who Rigg finds out is a serial rapist. He forces Landsness onto a bed, which blinds only one of Landsness' eyes, and the trap dismembers him. Rigg is led to a school, where he finds a married couple, Rex, who is already dead, and Morgan, who already has her spikes pulled out of her body. Morgan pulls out her last spike and Rigg gives her a key to save herself. Rigg turns on a fire alarm and goes to the location of his final test.
The agents alternate between investigating the scenes and questioning Jill Tuck, Kramer's ex-wife. Jill reveals Kramer's work with civil engineering and property development, and that she miscarried her son Gideon after seven months when Cecil Adams, a drug addict, slammed a door into her stomach while robbing her health clinic. At the motel, the agents learn that the room was rented out to a lawyer named Art Blank, who vanished two weeks prior, and survivor of the mausoleum trap. Blank is revealed to be the man overseeing the game when he stops Matthews's attempts at jumping and gives him a gun. At the school, the agents learn that all three victims, as well as Jill, were Blank's clients. A crime scene photographer is killed by a trap, while Strahm and Perez find a puppet and a tape recorder in another room, which plays a cryptic message for Perez before its face explodes, sending shrapnel into her face. After Perez is hospitalized, Strahm furiously questions Jill, now convinced of Blank's involvement, and how Kramer ended his work with the wake of Blank's depression, and that Cecil became the first victim of Kramer's "games". Strahm connects her story and a prior clue to the Gideon Meatpacking Plant, the location of his final test.
Strahm arrives after Rigg, but ends up following Jeff Denlon. After finding Jeff in the sickroom, Strahm shoots him dead in self-defense when Jeff demands his daughter back. Meanwhile, Blank pulls out a device which will free them when the timer expires; if used before then, a pair of pincers will sever his spine. Rigg finds them and is shot by Matthews as he breaks into the room, releasing two overhead ice blocks which swing down and crush Matthews' head, killing him. Rigg shoots and kills Blank, believing him responsible for the game, only to learn from Blank's tape recorder that his interference caused Matthews' death. Hoffman, the actual accomplice, releases himself from the chair, but leaves Rigg to bleed to death. He seals Strahm in the sickroom and leaves the plant. The scene cuts to Hoffman at the morgue, which implies that John's autopsy took place after the events of the film.
Saw IV’s writers were Thomas Fenton, Marcus Dunstan, and Patrick Melton. There was also a hunt for a director before it was officially stated that Darren Lynn Bousman would direct the fourth installment, with creators and executive producers James Wan and Leigh Whannell also returning. Principal photography took from 16 April 2007 to 3 May 2007. The filming location was Toronto, Ontario; the same place both Saw II and Saw III were filmed. The post-production period began on 19 May.
In an interview with Bousman, he stated that the last work on Saw IV would happen in August to be able to have prints made. At Comic Con 2007, it was revealed by Bousman and producer Mark Burg that the MPAA had given the film an NC-17 rating. They would have to figure out whether or not to cut the film to achieve an R rating or release it as an NC-17 film, the former of which they accomplished.
Lionsgate held its fourth annual “Give Til It Hurts” blood drive for the Red Cross.
The film grossed $63,300,095 in the United States and an additional $71,228,814 internationally, bringing the theatrical total to $134,528,909. It is Lionsgate's sixth highest-grossing film in the United States and Canada.
Critical reception to Saw IV was negative. Rotten Tomatoes reports that 17% of critics gave the film a positive review, based upon 75 reviews, with an average score of 3.7 out of 10. The Rotten Tomatoes consensus states: “Saw IV is more disturbing than compelling, with material already seen in the prior installments.” On Metacritic, the film has an average score of 36 out of 100, based on 16 reviews. Scott Schueller from the Los Angeles Times called it “a film as edgy as a rubber knife” and said that “if the terrible craft of Bousman's film doesn’t turn your stomach, the borderline pornographic violence will. It’s disconcerting to imagine anyone enjoying the vile filth splashing the screen.” Frank Scheck from The Hollywood Reporter said “the famously inventive torture sequences here seem depleted of imagination”, but added that “it hasn’t yet jumped the shark like such predecessors as the Nightmare on Elm Street and Friday the 13th movies eventually did.” Peter Hartlaub from The San Francisco Chronicle called it “the Syriana of slasher films, so complicated and circuitous that your only hope of understanding everything is to eat lots of fish the night before and then watch each of the previous films, in order, right before you enter the theater.” James Berardinelli wrote that “Saw IV functions as a drawn-out, tedious epilogue to a series that began with an energetic bang three years ago with Saw, then progressively lost momentum, coherence, and intelligence with each successive annual installment. Saw IV is nothing short of a money-grab. Despite a couple of loose ends (that are tied up unsatisfactorily here), Saw III finished the story.”
A less negative review came from Scott Weinberg from Fearnet, who said that while it "is almost certainly the weakest of the series where stuff like plot, logic, and chills are concerned... there's still more than enough here to keep the fans intrigued, entertained, and squirming in their seats" and added that the "Saw-makers are to be commended for actually putting forth this sort of effort. I grew up in an era that offered little more than quick-cash, stand-alone horror sequels like Halloween 5 and Friday the 13th Part 7 — so the fact that these producers actually give a damn about narrative continuity (right down to the smallest detail) is fairly impressive." Horror.com said that "with Saw IV, the pieces have all come together and [it's] the best of the lot." Jamie Russell from the BBC called it "deeply unsettling; just like a horror movie should be." Chris Hewitt from St. Paul Pioneer Press claimed that "Saw IV is a fluid film, as neatly constructed as the deadly puzzles Jigsaw creates to snare his victims." Film School Rejects said that "One of the things that is most intriguing to me about the Saw movies is how much I actually have enjoyed them" and claimed that "As far as fourth installments in a series, Saw IV is quite impressive." Linda Cook from Quad-City Times gave it a positive review also and said "The twists and turns are deadly, the 'lessons' are taught once again, and we have the perfect setup for Saw V."
The Unrated Director's Cut was released on January 22, 2008 in America and March 3, 2008 in the UK, on DVD and Blu-ray. The "Extreme Edition", which was released in the UK only, before the release of Saw V in October 2008 features a 95-minute running time of the film.
This edition was only released in the United Kingdom.Exclusive automated spinning Saw with a sound clip packaging
A copy of the Saw: Rebirth comic
Two audio commentaries (one with director Darren Lynn Bousman and actor Lyriq Bent; the other featuring the producers)
Video diary of Darren Lynn Bousman
Traps of Saw IV
Props of Saw IV
Music Video "I.V." by X Japan
The soundtrack was released on October 23, 2007 by WEA/Warner Bros. Records.