Louis Salinger, a British ex-Scotland Yard officer-turned Interpol detective, and Eleanor Whitman, an Assistant District Attorney from Manhattan, are investigating the International Bank of Business and Credit (IBBC), which funds activities such as money laundering, terrorism, arms trading, and the destabilization of governments. Salinger's and Whitman's investigation takes them from Berlin to Milan, where the IBBC assassinates Umberto Calvini, an arms manufacturer who is an Italian prime ministerial candidate. The bank's assassin diverts suspicion to a local assassin with political connections, who is promptly killed by a corrupt carabiniere. Salinger and Whitman get a lead on the second assassin, but the corrupt carabiniere comes in again and orders them out of the country. At the airport they are able to check the security camera footage for clues on the whereabouts on the bank's assassin, and follow a suspect to New York City.
In New York, Salinger and Whitman are met by two New York Police Department (NYPD) detectives, Iggy Ornelas and Bernie Ward, who have a photograph of the assassin's face when he arrived in New York airport. Salinger, Ornelas, and Ward locate Dr. Isaacson to whose practice the assassin's leg brace has been traced. They find the assassin and follow him to the Solomon R. Guggenheim Museum.
Jonas Skarssen, the chairman of the IBBC, reveals to his senior men White and Wexler that the bank had Calvini killed so that they could deal with his sons to buy missile guidance systems in which the bank has invested. Since the bank knows that Salinger and Whitman are close to finding their assassin, they send a hit team to kill him at a meeting between him and his handler, Wexler. Wexler leaves and is arrested by Ornelas. As Salinger and Ward speak to the assassin and attempt to arrest him, a shootout at the Guggenheim erupts when a number of gunmen attempt to kill them with automatic weapons. In the chaos Ward is killed, and Salinger is forced to team up with the assassin to fight off the gunmen. Despite escaping, the assassin is mortally wounded and dies of his injuries, thus losing another lead in Salinger's investigation.
In interrogation, Wexler, a former Stasi colonel, explains to Salinger that the IBBC is practically untouchable because of its utility to terrorist organizations, drug cartels, governments, and powerful corporations of all complexions. Even if he succeeds in bringing the IBBC down there are hundreds of other banks that will replace them. If Salinger wants justice, he needs to go outside the system, and Wexler indicates a willingness to help. Salinger persuades Whitman to let him go on alone.
In Italy, Salinger tells the Calvini brothers of the IBBC's responsibility for their father's murder, prompting them to cancel the deal with the bank and transmit orders for White to be killed. Salinger then accompanies Wexler to Istanbul, where Skarssen is buying the crucial components from their only other manufacturer. Salinger attempts to record the conversation so that he can obstruct the deal by proving to the buyers that the missiles will be useless, but he ultimately fails. Both Wexler and Skarssen are then killed by a hitman contracted by Enzo and Mario Calvini to avenge their father's murder by the bank. Salinger is left stunned, his investigation, pursuit, and determination to bring down the IBBC, have led him to nothing.
During the closing credits, it is indicated that the bank is successfully continuing with its operations despite the death of its Chairman—as Skarssen had predicted to Salinger before he was killed. However, with the new and more aggressive chairman, it is hinted that the IBBC's increased expansion and aggression will ultimately lead to its downfall, as shown by the last panel, revealing the beginnings of a United States Senate investigation, headed by Whitman.
Clive Owen as Louis Salinger
Naomi Watts as Eleanor Whitman
Armin Mueller-Stahl as Wilhelm Wexler
Ulrich Thomsen as Jonas Skarssen
Michel Voletti as Viktor Haas
Patrick Baladi as Martin White
Jay Villiers as Francis Ehames
Fabrice Scott as Nicolai Yeshinski
Haluk Bilginer as Ahmet Sunay
Luca Barbareschi as Umberto Calvini
Alessandro Fabrizi as Inspector Alberto Cerutti
Axel Milberg as Klaus Diemer
Brían F. O'Byrne as The Consultant
Felix Solis as Detective Iggy Ornelas
Jack McGee as Detective Bernie Ward
Nilaja Sun as Detective Gloria Hubbard
Steven Randazzo as Al Moody
Tibor Feldman as Dr. Isaacson
James Rebhorn as New York D.A.
Remy Auberjonois as Sam Purvitz
Ian Burfield as Thomas Schumer
Ben Whishaw as Rene Antall