Saw 3 follows Jigsaw and his apprentice Amanda as they continue to set deadly traps for their victims in order to test their will to live. Meanwhile, a couple of detectives, Eric Matthews and Kerry, hunt down Jigsaw and Amanda as they try to put an end to their reign of terror.

The story revolves around Jeff, a surgeon whose terminally ill son is kidnapped by Jigsaw and his followers. To save his son, Jeff must play one of Jigsaws games, involving a series of deadly traps. With the help of a few remarkable allies, Jeff battles his way through the dangerous games, only to uncover a sinister plot by Jigsaw to initiate a new generation of killing games.

As the story progresses, we discover more of Jigsaws schemes and learn the reason why he has chosen to single out Jeff. Meanwhile, Eric and Kerrys investigations become more urgent as they uncover evidence of Jigsaws plans to set up further traps and games.

The lives of all involved hang in the balance, as Jigsaws plans come together with deadly consequences. In the end, Jeff is forced to make a difficult choice that could save his son, or change the course of Jigsaws plans forever.