The film features the Jigsaw Killer being apprehended by the police, but trapping the arresting officer in one of his own games while showing another "game" of eight people—including the officer's son in progress on TV monitors at another location. It also explores some of the Jigsaw's back story, providing a partial explanation for why he chose to become "Jigsaw".
Upon release, Saw II received mostly negative reviews from film critics. Some dismissed the film as being a "Se7en knockoff", "lacking style and plot" and some revolting over the "explicit gore and torture scenes", while others praised it as being a "worthy follow-up" and "providing plenty of what fans of the first expected". Despite negative reviews Saw II was a financial success grossing $31,725,652 its opening weekend, recouping its $4 million budget. The film currently is the highest grossing (domestically) Saw film to date.
Michael Marks (Noam Jenkins), a police informant, awakens to find two halves of a spike-filled helmet locked around his neck. A videotape informs him that the key to the trap has been implanted behind his right eyeball. He finds a scalpel but cannot bring himself to cut out his eye, and is killed instantly when the helmet slams shut around his head when time runs out.Detective Eric Matthews (Donnie Wahlberg) is called to the scene after a message is found on the wall directed at him. Later, he follows Detective Kerry (Dina Meyer) and a SWAT team led by Sergeant Rigg (Lyriq Bent) to an abandoned steel factory, where they find John Kramer, who is seriously weakened from his cancer. Computer monitors in John's lair show that eight people are trapped in an abandoned house: among them are Matthews' son, Daniel (Erik Knudsen), who he previously argued with, and Amanda Young (Shawnee Smith), Jigsaw's only known survivor. The eight victims have two hours before the nerve gas filling the house kills them, but John promises Matthews that he'll see his son "in a safe, secure state" if he simply talks with John for a while. Reluctantly, Matthews agrees to the conditions in order to buy time for the tech team to arrive and trace the video signal.
In the nerve gas house, the eight victims are told that antidotes can be found around the house to save them from the gas. Gus Colyard (Tony Nappo) is shot dead by the door to the room, which is booby-trapped with a revolver, when Xavier Chavez (Franky G) accidentally triggers it. The search continues to the basement, where the group learns that one of them, Obi Tate(Timothy Burd), was an accessory to the kidnappings; he had kidnapped Laura Hunter(Beverley Mitchell), who shows more strain from the gas than the others. Obi attempts to retrieve two antidotes from a small furnace, but is burned alive when he unintentionally activates it. As Amanda reveals to Daniel that she was framed for her possession charge which sent her to prison, Jonas Singer (Glenn Plummer) leads them to a door, which Xavier and Addison Corday (Emmanuelle Vaugier) are attempting to force their way through. In the room is a pit filled with thousands of needles and syringes; a key to an antidote is hidden inside. The trap is intended for Xavier, but he instead throws Amanda into the pit; she retrieves the key, but Xavier fumbles with it and fails to unlock the door in time. Frustrated with the group's lack of success, he abandons the others.
Meanwhile, John explains to Matthews how he came to begin his "work": after being diagnosed with cancer, he attempted to commit suicide by driving off a cliff, but survived the crash and vowed to spend the rest of his life testing others' wills to survive. When the tech team finally arrives, John reveals to Matthews that the seven victims aside from Daniel are criminals that Matthews himself framed for various crimes; should Daniel's identity be discovered, he will be in great danger. In an effort to make John reveal the location of the house, Matthews destroys several of John's plans and work, but fails to get a reaction.
Xavier returns to the first room, which contains a safe containing an antidote, and discovers a colored number on Gus' neck; he realizes by connecting this to their first clue that one colored number is on the necks of each victim. He kills Jonas in a fight and begins stalking the other victims. In another area of the house, Laura finally succumbs to the nerve gas, and the others learn of Daniel's identity. Addison and Amanda both abandon him, but Amanda quickly returns when she discovers Xavier advancing on them. Addison, meanwhile, finds an antidote in a glass box with arm sockets lined with razor blades, which her wrists get trapped in; Xavier finds her, but leaves her to die after reading her number. Amanda and Daniel retreat to the safe room, where they discover an underground tunnel that leads to the bathroom of the first film; (where Adam's corpse and Zep's corpse is seen in a progressive state of decomposition ) Daniel collapses upon entering. When Xavier arrives, Amanda points out that he cannot read his own number; he cuts off a piece of skin from the back of his neck, then advances on the two, upon which Daniel attacks and kills him with a hacksaw, having only feigned collapse.
Detective Matthews loses control after seeing Xavier begin chasing Daniel and Amanda and violently attacks John, eventually forcing him to take him to the house at gunpoint. The section that John was sitting in is revealed to be an elevator, allowing him and Matthews to escape. Simultaneously, the SWAT team follow the signal of the video feed to another house, which contains VCRs playing back previously recorded images of the eight victims; Kerry realizes that the events of the house took place before they raided the factory. Matthews enters the house and eventually reaches the bathroom, where he is attacked by a figure wearing a pig mask. The two-hour timer expires in John's lair and a large safe opens, revealing Daniel hyperventilating into an oxygen mask. Upon awakening, Matthews finds himself chained by the ankle to the pipes; an audiotape lying beside him, recorded by Amanda, reveals that she has become John's protege. She appears in the doorway and seals the bathroom door shut with Matthews inside while outside the house, a bloodied John slowly forms a smile. Amanda then leaves Matthews there to rot.
- Tobin Bell as John Kramer/Jigsaw
- Shawnee Smith as Amanda Young
- Donnie Wahlberg as Detective Eric Matthews
- Erik Knudsen as Daniel Matthews
- Franky G as Xavier Chavez
- Glenn Plummer as Jonas Singer
- Emmanuelle Vaugier as Addison Corday
- Beverley Mitchell as Laura Hunter
- Tim Burd as Obi Tate
- Dina Meyer as Detective Allison Kerry
- Lyriq Bent as SWAT Commander Daniel Rigg
- Kelly Jones as SWAT Pete
- Vincent Rother as SWAT Joe
- Noam Jenkins as Michael Marks
- Tony Nappo as Gus Colyard
''Saw II was released in New Zealand, the United States, and the United Kingdom on October 28th, 2005; and November 17, 2005 in Australia. The original teaser poster which showed two severed fingers was rejected by the MPAA. Since the poster was already released and managed to 'slip by' the MPAA, they issued a release stating the poster was not approved and was unacceptable. Lionsgate then removed the poster from their websites.'
Tobin Bell was nominated for "Best Villain" at the 2006 MTV Movie Awards for his role as Jigsaw, though the award went to Hayden Christensen for his role in Star Wars Episode III: Revenge of the Sith.
Critical reception to Saw II were generally negative. Rotten Tomatoes reports that 35 percent of critics gave the film a positive review, based upon a sample of 113, with an average score of 4.6 out of 10. On Metacritic, the film has an average score of 40 out of 100, based on 28 reviews. Critics found Jigsaw's diabolic "games" to require a large amount of planning and fortuitous timing in order to succeed, causing some to liken his murderous schemes to Rube Goldberg machines. Tobin Bell addressed some of these criticisms by saying, "My sense is that Jigsaw is so detail oriented that I think he thinks in terms of worst case scenario. I think he’s a very good judge of character, so his sense that, for example, that Detective Matthews was going to play right into his trap, which he did, was right on. Now, it seems to me that he’s always got a second plan in place. And there’s probably been a number of second plans. I mean, we’ve only seen three movies. Maybe there are six more somewhere where he failed, where something didn’t play out."
'Saw II opened with $31,725,652 in 2,949 theaters and went on to gross $87,025,093 domestically and $65,900,000 in foreign markets with a total of $152,925,093 in 10 weeks of being in theaters The film currently has the highest gross domestically within the Saw series. 
Unrated Special Edition
In this version, several changes have been made from the theatrical version:
*The opening scene with the "Venus Head Trap" is extended and the song "Irresponsible Hate Anthem (Venus Head Trap Mix)" is playing in the background.
- When the police are entering the Wilson Steel warehouse, three short cuts are shown of Jigsaw upstairs eating a bowl of cereal in front of him, realizing the police have arrived. When he realizes this, he calmly goes back to eating the cereal.
- Jigsaw has a few extra lines of dialogue with Detective Matthews, mentioning that he has "wiped the slate clean", and that most people are merely "sleepwalking".
- When Obi is trapped in the oven, he attempts to break the glass on the far side as he is burning alive.
- The scene of Amanda thrashing around in the syringe pit is extended to the full three minutes as shown on the timer.
- In the bathroom, Charlie Clouser's score is different and much harsher as Xavier cuts the back of his neck, than the similar music in the theatrical cut.
- The scene where Matthews is beating up Jigsaw is extended with one extra punch.
As with the first Saw, there is an easter egg called "See SAW II in Sixty II". It has three "takes", the first one is using clay figures modeled after the characters in the film, the second replaces the character with common materials, and the third one uses photos from the film which are animated.
- Spike TV's Scream Awards
- Nominated: Best Sequel
- Nominated: Most Memorable Mutilation (Stabbed in a pit of Needles)