SMERSH, the Soviet counterintelligence agency, plans to commit a grand act of terrorism in the intelligence field. For this, it targets the British secret service agent James Bond. Due in part to his role in the defeat of the SMERSH agents Le Chiffre, Mr Big and Hugo Drax, Bond has been listed as an enemy of the Soviet state and a "death warrant" has been issued for him. His death is planned to precipitate a major sex scandal, which will run in the world press for months and leave his and his service's reputations in tatters.
Bond's killer is to be the SMERSH executioner Red Grant, a psychopath whose homicidal urges coincide with the full moon. Kronsteen, SMERSH's chess-playing master planner, and Colonel Rosa Klebb, the head of Operations and Executions, devise the operation. They instruct an attractive young cipher clerk, Corporal Tatiana Romanova, to falsely defect from her post in Istanbul having, she would claim, fallen in love with Bond after seeing a photograph on his file. As an added lure for Bond, Romanova will provide the British with a Spektor, a Russian decoding device much coveted by MI6. She is not told the details of the plan.
The offer of defection is received by MI6 in London, ostensibly from Romanova, but is conditional that Bond collects her and the Spektor from Istanbul. MI6 is unsure of Romanova's motive, but the prize of the Spektor is too tempting to ignore; Bond's superior, M, orders him to go to Turkey. Once there, Bond forms a comradeship with Darko Kerim, head of the British service's station in Turkey. Bond meets Romanova and they plan their route out of Turkey with the Spektor. He and Kerim believe her story and the three board the Orient Express. Bond and Kerim quickly discover three Russian MGB agents on board, travelling incognito. Kerim uses bribes and trickery to have two of them taken off the train, but he is later found dead in his compartment with the body of the third agent, both—unbeknown to Bond—having been killed by Grant.
At Trieste a fellow MI6 agent, "Captain Nash", introduces himself and Bond presumes he has been sent by M as added protection for the rest of the trip. Romanova is suspicious of Nash, but Bond reassures her that the man is from his own service. After dinner, at which Nash has drugged Romanova, they rest; Bond wakes up to find a gun pointing at him and Nash reveals himself to be the killer Grant. Instead of killing Bond immediately, Grant reveals SMERSH's plan, including the detail that he is to shoot Bond through the heart and that the Spektor is booby-trapped to explode when examined. As Grant talks, Bond places his metal cigarette case between the pages of a magazine he holds in front of him, positioning it in front of his heart to stop the bullet. After Grant fires, Bond pretends to be wounded; when Grant steps over him, Bond attacks and Grant is killed. Bond and Romanova escape.
Later, in Paris, after successfully delivering Romanova and the booby-trapped Spektor to his superiors, Bond meets Rosa Klebb. She is captured but manages to kick Bond with a poisoned blade concealed in her shoe; the story ends with Bond fighting for breath and falling to the floor.