Two CIA agents Jim Brady and Ann Turner escape from a military complex in the Middle East after trying to steal a canister of biological material. A high-speed boat chase follows until eventually they outrun their pursuers and set off overland to find the aircraft they flew in on.
After arriving back at their operations base they find the canister they stole contained nothing. The batch they were after had been moved hours before they got there.
The scene switches to London where an unknown terrorist cell attempts to plant a device in the London underground. This failed after the person planting it electrocutes himself on the live rail. The device is quickly found and brought to the surface for testing, where they discover it contains anthrax.
MI5 and the antiterrorist branch of Scotland Yard are unable to identify the body at first. But with the help of the CIA they eventually discover who he is, and link him to a suspect they've been watching.
The suspect, who assembled the device, is instructed to meet the third member of the cell to explain why the plot failed. After the meeting he is caught heading back to London by MI5, and following interrogation agrees to become a double agent.
After what happened in London. The British Prime Minister and the American President meet in Washington, and agree to a joint operation to hunt down the terrorists.
The CIA pick up a coded message from a phone intercept, which suggests the group who attempted to release anthrax in London are going to try again in Washington. Realising this the British and American secret services set out on a joint mission to kill or capture the group.