Dr. Watson has agreed to locate a friend's drug-addicted husband and while searching through an opium den, is surprised to find Sherlock Holmes there. Holmes is attempting to solve the disappearance of Neville St. Clair. Several days before, Mrs. St, Clair had been walking in a rundown section of London when she looked…

The main story is set in a British Military Intelligence Office in Whitehall during 1956, where a small group of foreign affairs analysts find their quiet existence disrupted by the Suez Crisis. Ewan McGregor plays Mick Hopper, who is doing his national service as an interpreter of Russian documents. Bored with his job…