James Bond, agent 007 with Her Majesty's Secret Service, is sent to a health clinic to recover from over-drinking and over-smoking. During his stay, he tangles with a criminal who, unbeknownst to Bond, is involved in an international blackmail scheme. Soon, Bond is whisked off to the Bahamas in search of SPECTRE, a criminal organization threatening to explode stolen nuclear bombs. Bond finally foils these modern-day pirates in a spectacular underwater battle.

The novel opens with Bond in a depressed state. With nothing but paperwork to do, he has given in to drinking, smoking, and gambling. M sends him to Shrublands, a natural health clinic, to recover. While there, Bond detects a criminal named Count Lippe. Bond does not know much, but apparently it is too much. Lippe attempts to eliminate Bond, and in retribution, Bond badly burns Lippe in the Turkish bath.

Meanwhile, the international organization SPECTRE, run by the sinister criminal Ernst Blofeld, has stolen a plane carrying two nuclear warheads. SPECTRE threatens to detonate them unless the western world pays them 100 million pounds in gold bullion. On a slim lead, Bond is sent to the Bahamas to track down the criminals and find the nuclear bombs.

Bond finds Largo, a smarmy criminal, and his beautiful mistress Domino. Largo's cover is perfect. This modern-day pirate and his crew of SPECTRE operatives are disguised as treasure hunters, seeking a sunken ship full of pirate treasure. Bond is joined by CIA operative Leiter, and they discover Largo's expensive hydrofoil yacht has a secret compartment for underwater work. Then, they find the crashed plane and the dead bodies of its crew. The pilot who brought in the plane was Domino's brother, and Largo had him killed in a double-cross.

Faced with the news of her brother's death, Domino agrees to take a Geiger counter on board the yacht and signal the watching police when she detects the bombs on board. She is caught and tortured. Meanwhile, Bond and Leiter attempt to intercept Largo's yacht in a nuclear-powered submarine and stop the first bomb from destroying a British base on Grand Bahama.

Bond and Leiter lead a team of U.S. Navy men armed with makeshift spears to ambush the SPECTRE men on their way to plant the bomb. As the underwater battle rages, Bond is locked in a fight to the death with Largo. Their weapons are lost, and finally the two face each other among the coral reef. Largo blinds Bond with an octopus, and Bond retaliates with a rock.

Largo gains the upper hand and is choking Bond in a stranglehold, when Domino appears with a spear gun and spears Largo through the neck. At the verge of death, the Domino and Bond make their way to the surface. When the weakened Bond awakens, he learns both warheads have been recovered and Domino will be fine. However, Blofeld has escaped. Still drugged, Bond makes his way to Domino's room and collapses by her bedside. The world is saved, for now.