Richard Hannay arrives in London on the eve of World War I, where he meets an American agent seeking help in stopping a political assassination. Before long, Hannay finds himself in possession of a little black book that holds the key to the conspiracy and on the run from both the police and members of a mysterious organization that will stop at nothing to keep their secrets hidden.
The book has formed the basis for a number of film adaptations, notably: Alfred Hitchcock's 1935 version; a 1959 color remake; a 1978 version which is perhaps most faithful to the novel; and a 2008 version for British television.