In 2044, 25-year-old Joe works for a Kansas City crime syndicate as a “looper”. Since future tracking systems have made it nearly impossible to dispose of victims’ bodies, the syndicate uses time travel. Managed by a man from the future named Abe, loopers kill and dispose of victims whose faces are concealed. The assassins are paid with silver bars that are strapped to their targets. To prevent connections to the syndicate, a looper’s final victim will be his or her retired future self. These targets are identified by gold bars strapped to them instead of silver. Killing one’s future self ends the contract and “closes the loop”.
Joe’s friend Seth confesses to Joe that he has not killed his future self. Old Seth has escaped, after warning Seth that a person in the future called the Rainmaker will overthrow the five major bosses and close all loops. Joe reluctantly hides Seth in his apartment’s floor safe, but when Kid Blue, one of Abe’s elite “Gat Men”, takes Joe to Abe, Joe reveals Seth’s location. Abe’s men cut an address into younger Seth’s arm and then begin severing body parts. These effects appear on Old Seth’s body; he goes to the address that has appeared on his arm and is killed.
When Joe’s next target arrives, it is his older self, but with his face uncovered and hands unbound. Old Joe escapes before Joe can kill him. Returning to his apartment, Joe fights with Kid Blue, falls off a fire escape and blacks out.
In another timeline, Joe does kill his older self. He moves to Shanghai and becomes a hitman to finance his drug addiction and wild lifestyle. Eventually, he marries. Seven years later, his wife is killed when Joe is taken to close the loop. Overpowering his captors, Old Joe sends himself back to 2044, altering his history by evading Joe and escaping.
Old Joe experiences vague memories of Joe’s actions in the present, and meets his younger self at a diner. He wants to alter history again and save his wife by killing the Rainmaker as a child. He acquires a map from a local library using numbers written on his hand that are supposed to pertain to the Rainmaker’s identity. Kid Blue and the Gat Men appear, and a gunfight ensues. Both Joes escape, with pieces of the map.
Joe follows the map to a farm where Sara and her son, Cid, live. Sara recognizes the numbers on the map as Cid’s birthday and birth hospital’s zip code. Joe guesses that Old Joe is going to kill all three children born at that hospital on the same day, not knowing which one will become the Rainmaker.
Jesse, a Gat Man, comes to the farm, but Cid and Joe hide. Later that night, Sara and Joe have sex, and Sara reveals that she has above-average telekinetic powers. Cid’s powers are even stronger. In the morning, Joe wakes to find Jesse holding Sara at gunpoint. Terrified, Cid kills Jesse using telekinesis. Joe realizes that Cid will become the Rainmaker and that Old Joe will now know this.
Kid Blue captures Old Joe and takes him to Abe. Old Joe breaks free, killing Abe and his henchmen, and goes to Sara’s farm, followed by Kid Blue. While Young Joe kills Kid Blue, Old Joe pursues Sara and Cid. When Cid’s face is grazed by a bullet, Sara calms him before he can react and kill them. She sends Cid into the cane field and stands between Old Joe and her son. Joe realizes that Sara’s death will turn Cid into the Rainmaker. He commits suicide, erasing Old Joe’s existence, saving Sara and potentially preventing Cid from becoming the Rainmaker.