Silvia Broome (Nicole Kidman) is an interpreter working at the United Nations in New York, who was raised in the Republic of Matobo, a fictional African country.
The United Nations is considering indicting Edmond Zuwanie (Earl Cameron), president of Matobo, to trial in the International Criminal Court. Initially a liberator, over the past 20 years he has become as corrupt and tyrannical as the government he overthrew, and is now responsible for ethnic cleansing and other atrocities within Matobo. Zuwanie is soon to visit the United Nations and put forward his own case to the General Assembly, in an attempt to avoid the indictment.
A security scare forces the evacuation of the UN building, and Silvia returns at night to reclaim some personal belongings. At that time she overhears discussion of an assassination plot, and runs scared from the building when those discussing the plot become aware of her presence. The next day, Silvia recognises words in a meeting where she is interpreting from phrases she overheard the night before, and reports the incident to UN security; the target of the plot appears to be Zuwanie himself. They, in turn, call in the United States Secret Service, who assign Tobin Keller (Sean Penn) and Dot Woods (Catherine Keener) to investigate, as well as protect Zuwanie when he arrives. Keller learns that Silvia has, in the past, been involved in a Matoban guerrilla group, that her parents and sister were killed by land mines laid by Zuwanie, and that she has dated one of Zuwanie's political opponents. Although Keller considers Silvia a prime suspect, the two grow close and Keller ends up protecting her.
The assassin is discovered while Zuwanie is in the middle of his address to the General Assembly, and security personnel rush Zuwanie to a safe room for his protection. In the confusion, Silvia attempts to take revenge on Zuwanie for all that has happened, and Keller arrives just in time to prevent her from murdering him. The assassination plot is revealed to be a sham; Zuwanie planned it to enhance his own credibility, and thus avoid the indictment, while also eliminating his political opponents. Zuwanie is indicted, and Silvia is expelled from the UN, returning home to Matobo soon afterwards.