Physicist Jane Chandler is happily married to Matt and they have two kids. She has her own research lab and together with her assistant, Regg, they discover a way to send objects to a parallel world. Later, tragedy strikes: Matt is killed in a car crash. Grieving, Jane travels to the parallel world and finds another version of her husband, who she brings back to her world. Gradually he reveals himself to be a very different man. He carries a strange, deadly weapon and has a terrible temper. Fearful she has made a mistake, Jane takes a second trip to the parallel world to find out more about him. While Jane is in the parallel world, he breaks into the lab in the first world, kills Regg and destroys the machine. Now Jane is trapped in the parallel world and her kids are at the mercy of a murderer. The next day Regg #2 appears at the lab. He tells her that he has built a duplicate machine. Jane finds a way to teleport back to her world to confront Matt #2 and rescue her kids.