When waking from sleep, Captain Colter Stevens (Jake Gyllenhaal) do not recognize his own body. Colter trapped in the body of another person. Soon Colter remembered that he was in a dangerous assignment. Colter had to find know the train bombers.
Captain Colter Stevens is actually part of an experiment by the government. This experiment is called the Source Code, who makes Colter can get into the body of another person. Currently Colter was in the body of a man named Sean Fentress who becomes the passenger of a train who exploded due a bomb.
Colter could repeat the train wreck until he found who the perpetrators of the bombing so he could prevent the recurrence of accident. What will be done by Colter? Can he save the train passenger that crashed?