We see, from the end of the first Saw movie, Cary Elwes as Dr. Lawrence Gordon crawling, leaving a trail of blood from the bloody stump that remains after he cut his leg off. He is dragging himself in order to escape. Along the way, he reaches for a pipe to pull himself up but realises it’s red hot. He then swings himself around to press the stump against the pipe to cauterise the wound.
Somewhere else in the world people on a street start paying attention to something. A crowd gathers. In a store front window two guys, Brad and Ryan, wake up attached to a contraption. Each has a circular saw blade in front of his face. They are surrounded by mannequins dressed as construction workers.
People at the window start making phone calls; it’s very voyeuristic.
Now we see that there is a circular saw blade in the middle too. A scantily clad woman is tied to the ceiling above. Brad and Ryan appear to know the woman.
Jigsaw’s puppet comes in and reveals that this woman has been playing each of the guys against the other romantically. It says something about damaging both of the guys. Her fun and games even led both of them to break the law.
They’re told that they have 60 seconds. In that time she will drop and the only way to save her is for one of them to pull or push the blades either into themselves or the other guy via a sliding mechanism. Each tries pushing a blade into the other. One cuts the other up a little.
The woman tells Brad she loves him, but after he fails she tries to convince Ryan to kill Brad and save her.
But it doesn’t work. They wait and allow her to be lowered onto the saw.
An onlooker who has tried to break the glass with a briefcase earlier appears to be the one who called the cops. It’s likely she’ll have a bigger part elsewhere. All the while bigger crowds are watching aghast. Police start to arrive, but they can’t break the glass.
The woman’s body is cut in two through her stomach. There’s blood on the glass, blood on the puppet. Her guts fall onto the floor.