Plot
Major Bennett Marco commanded a U.S. Army unit during the Persian Gulf War in 1991. Sergeant First Class Raymond Shaw was awarded the Medal of Honor for actions following an enemy ambush of his reconnaissance patrol in Kuwait. Shaw led all but two survivors of the patrol on a three-day escape through the desert. Shaw is now a U.S. congressman whose ruthless mother, Virginia Senator Eleanor Prentiss Shaw, uses her influence to secure his nomination as the vice-presidential candidate over the favorite, Senator Tom Jordan. Shaw also resents her role in the break-up of his relationship with childhood sweetheart Jocelyn, Senator Jordan's daughter, prior to his enlistment.
One of Marco's former soldiers, Al Melvin, confesses to him he's having confusing dreams about the ambush, in which the patrol's soldiers are captured, tortured and brainwashed. Marco feels compelled to investigate and travels to New York City. En route he meets an outgoing supermarket clerk named Rosie who knows his name. Marco accepts her offer of lodgings. While showering at her apartment, he digs at a small lump he finds on his upper back and dislodges a metal object that falls down the sink after Rosie forces her way inside the bathroom in response to his sounds of distress.
Marco confronts Shaw at campaign headquarters, wrestles him to the ground and bites his back to remove an implant he suspects is there. Marco is arrested and released when Shaw refuses to press charges. He returns to Rosie's apartment still concealing Shaw's implant in his mouth. His friend Delp analyzes it, and surmises its purpose was storage of emergency medical data. He is aware of a parallel project for implantables funded by Manchurian Global, a powerful private equity firm with major political connections, including Senator Shaw. Delp administers electro-convulsive therapy with methohexital to Marco and he summons clearer recollections that he was brainwashed during the mission, and that the two missing soldiers were in fact killed by him and Shaw. He learns he's under surveillance when he discovers microcassettes in Rosie's handbag containing recordings of their conversations.
His research on Manchurian Global in the public library produces the name of Dr. Atticus Noyle, a South African geneticist accused of human experimentation on political prisoners during Apartheid who is involved in scientific research for Manchurian Global regarding novel memory implants. He shows his findings to Senator Jordan, who confronts the Shaws by connecting Dr. Noyle's work on deep implant behaviour modification financed by Manchurian Global during Desert Storm, Marco and Shaw's three day disappearance in the desert, and subsequent dreams and recollections of the patrol's members. When he suggests that Shaw withdraw from the campaign, Eleanor "activates" Shaw and orders him to kill Jordan. Jocelyn is killed trying to stop Shaw from murdering Jordan.
Marco confronts Rosie who reveals she's been surveilling him for the FBI. Knowing Melvin to have carried an implant and that he died mysteriously like the other members of the patrol, the FBI arranges to meet Marco and Shaw to convince them they were brainwashed under an assassination plot. Governor Arthur and Shaw win the White House. Shaw receives a phone call intended for Marco from Eleanor. She uses trigger words to command Marco to assassinate the President-elect so that Shaw will become president, admitting she voluntarily gave him to the brainwashers for the country's benefit. Shaw resists the mind-control techniques, empowered by Jocelyn's death, and deliberately places himself between the entranced Marco and the President-elect. As Rosie rushes through the crowd to find Marco, Shaw gives the signal to kill him and his mother. Shaw dances with Senator Shaw, leading them into the pre-arranged position, where Marco kills them both with a single rifle shot. Marco prepares to kill himself, but Rosie prevents his suicide by wounding him.
The FBI frames a deceased Manchurian Global contractor as the shooter. Manchurian executives watch in defeat as the conspiracy is revealed on live television. Rosie takes Marco to the remote island compound where he was conditioned. After reflecting on his time there, Marco drops a photo of his Army unit and Shaw's Medal of Honor into the sea.