On July 1, 1968 America, Britain and Russia signed a treaty to halt the spread of nuclear weapons. The powers then added four secret extra clauses. The most secret and dangerous of them was and remains, the last. One winter, the Chairman of the KGB hatches a plan to breach this Fourth Protocol and destroy Nato. He sends an agent, Major Petrofsky - Pierce Brosnan - to assemble the operation. A British spycatcher, John Preston - Michael Caine - must race against an unknown deadline to stop him and his devastating mission.