In London, England, Professor Robert Elliot, a special advisor on economic affairs for the U. S. Foreign Relations Committee, discusses inflation with a panel of experts on a television news program called “The World This Week.” Also on the panel is Jean Robertson, an American journalist for the Washington Post, who argues with Elliot about the U. S.’s exploitation of foreign countries for economic benefit. Afterward, Jean, who once had an affair with Elliot, asks the professor to join her for dinner later in the week. The following day, Jean gets an assignment to report on E. J. Farnsworth, an American businessman who is coming to London. When Farnsworth arrives on a private plane, Jean learns via telex that he is the vice president of International Oil, an “acting attorney” for several corporations, and Chief Advisor to the Central Committee on U. S. Foreign Economic Relations. Her superior at the Washington Post finds Farnsworth’s London trip suspect. At the exclusive Director’s Club, Elliot and Jean attend a reception. There, Farnsworth asks Elliot to play golf and he accepts, though Jean later warns him to stay away from corrupt people like Farnsworth. The next day, Farnsworth asks Elliot if he’d like to be chairman of the U. S. President’s Economic Advisory Committee, promising a hefty salary. Elliot expresses interest, but when Farnsworth asks who has been providing him secret information in London, Elliot confesses that he has four informants. Farnsworth says that the four people will have to be killed before Elliot is appointed, as the U. S. government cannot risk hiring anyone with contacts who might blackmail him in the future. Though Elliot is shocked by the suggestion, he devises a plan to kill his informants – Alex Hellman, David Baker, Christina Larsson, and Bert Parsons – and calls it “The Internecine Project.” One night, Elliot breaks into a mortuary and cuts a piece of skin off of a corpse, collecting it in a plastic bag. He later speaks with Alex Hellman, who works for the British government, saying that Bert Parsons must be killed or Alex’s dealings with a military junta in Morocco will be exposed. Later, David Baker, a scientist, delivers a radio transmitter to Elliot, explaining that the device is capable of killing human beings with only the noise it emits. Elliot thanks David for the device, saying that it will be used in a trade for oil with some Middle Eastern contacts. Elliot then tells David that a contact of his, Alex, has become a security risk, and David must kill him in order to protect their collaboration from becoming public knowledge. Elliot promises that David will never have to meet Alex in order to kill him; instead, he will deposit a bottle of insulin inside the man’s house according to Elliot’s instructions. David refuses, but Elliot threatens to reveal the secret weapons David has created for foreign interests. Next, Elliot visits Christina Larsson, a call girl who passes along secret information gleaned from her clients. He asks Christina to hide David’s radio transmitter inside an apartment, sparing her the information that the device will be used to murder David. Finally, Elliot visits Bert Parsons, a masseur from the Director’s Club, and informs him of a “security leak” involving Christina. Bert, who admits to hating all women, suggests that he kill her, and Elliot pretends to be scandalized by the idea but agrees to it. Later, Jean and Elliot dine together at a restaurant, and Jean admits that she loved Elliot years ago. After dinner, they make love, but Jean cries, heartbroken over their casual affair. On a Friday night when Elliot has arranged for his informants to commit their murders, he monitors a phone in his office, waiting for each person to call and report on their whereabouts. At Alex’s apartment, David successfully replaces Alex’s regular insulin with a fatal dose, but calls Elliot to say that he was spotted on his way out. Meanwhile, at David’s apartment, Christina hides the radio transmitter under his couch and leaves. Jean surprises Elliot at home, but he coldly sends her away, saying that he is busy. After David calls to report that he is back home, Elliot activates the radio transmitter hidden under David’s couch, and the device sounds, killing David within seconds. When Christina returns to her apartment and showers, Bert breaks in and strangles her, placing the skin Elliot stole from the mortuary under her fingernails as Elliot instructed. Soon after, Alex calls Elliot to say he cannot murder Bert, but Elliot warns Alex that he will be killed if he doesn’t go through with it, and Alex subsequently bludgeons Bert to death outside the Director’s Club. Alex returns home but fails to call Elliot upon arrival, instead injecting the fatal dose of insulin that David left behind. Concerned that he has not received word from Alex, Elliot goes to Alex’s home and finds him passed out on the couch. Alex wakes up at the sound of Elliot’s voice, and though he is able to stand and begin a conversation, he soon drops to the floor and dies. With the Internecine Project completed, Elliot returns home and burns all associated paperwork. After hearing that Elliot has received his new government appointment, Jean visits his office to offer congratulations; however, Elliot is distant, and, in response, Jean informs him of her plans to write an article about the corruption of corporate influence over the U. S. government, promising that Elliot’s name will be mentioned. On his way to the airport in the backseat of a chauffeured car, Elliot opens an anonymous package and finds a diary with a message from David, explaining that the diary will have arrived only if David is dead. David’s note further explains that the pages are covered in a poison he invented, and Elliot will be dead within five minutes of touching them. At the airport, awaiting journalists find Elliot dead inside the car.