When Richard Hannay returns to London after an action-packed life in Rhodesia, he finds life unbearably dull. He is on the point of leaving the city in search of adventures, when mystery and intrigue turns up at his door in the shape of Franklin Scudder, Hannay's neighbour, who turns out to be a spy trying to escape the clutches of a shady international organisation, bent on sparking a European war.

When Scudder is mysteriously murdered and all the evidence seems to point to Hannay himself, he escapes to Scotland, bearing Scudder's cryptic coded notebook, which he struggles to decipher. Hannay manages by cunning, skilful disguise and sheer pluck to keep one step ahead of his ruthless pursuers...and eventually works out the cipher to read Scudder's mysterious notes, which refer to the 39 steps and the enigmatic Black Stone. But can Hannay solve the puzzle, thwart the criminals, and clear his name before Europe is plunged into turmoil?