In 2077, time-travelling assassin Joe Simmons (Joseph Gordon-Levitt) is one of the best in his field. Simmons (also known as a Looper) is recruited by the mafia to travel back 30 years to murder and dispose of anyone who threatens the goals of their organisation. At first, this task is no big deal, earning Simmons a lot of money, which plans to use to retire and get out of the game. When Simmons is sent to on a mission to kill his future self (Bruce Willis), he has to make the decision to "close the loop," and change the course of his life.