Dark Matter

Jason Dessen, a former quantum mechanics physicist, is a college physics professor who lives in Chicago with his wife Daniela and their son Charlie. One day Jason is kidnapped and drugged. He wakes up in a science laboratory and stumbles out of a metal cube. He discovers that he is in an alternate Chicago where, fifteen years previously, he had decided not to marry Daniela and had pursued his career as a physicist instead. In this world he built the cube that enables the occupants to move between the countless worlds created from every possible outcome of every event.
Jason is held and questioned by scientists in the laboratory. They believe he is the Jason from this world, referred to as Jason2, and is the first person to successfully return from a journey in the cube. Jason learns that Jason2 was his abductor who came to Jason's world to see what his life would have been like had he abandoned his career and married Daniela. Jason2 sent Jason to Jason2's world so that Jason2 could pretend to be Daniela's husband.
Determined to return to his own Chicago and his wife and son, Jason and Amanda (Jason2's therapist), escape and enter the cube. Unfamiliar with its operation, they find themselves transported to a number of parallel worlds. Eventually, Jason reaches his own world, where he finds Jason2 living with his wife and son. He convinces Daniela and Charlie that he is the real Jason, and takes them into hiding to evade Jason2. Jason2 finds Jason and attempts to kill him, but Jason mortally wounds his rival. To avoid the other belligerent Jasons who were created each time Jason made a new decision in his travels through alternate worlds, he flees with his family to the cube to start a new life in another world.