British agent James Bond, a foremost member of the "00" elite team, is rather annoyed that his superior, M, has made his participation in upcoming jobs contingent on completing a two week stay at Shrublands, a residential health farm where meals are very sparse, smoking is forbidden and the days involve various types of massage and treatment from chiropractors. Bond feels this is a waste of time and by the end of the third day is bored to tears and ravenously hungry. His interest is piqued during a massage when the man on the adjacent massage table is reluctant to remove his flashy, expensive wristwatch, revealing when he does so a distinctive tattoo. Bond calls his department and learns that the man, Count Lippe, must be a member of the equivalent of the Mafia in Macau. Unfortunately the Count hears this telephone call and attempts to kill Bond by cranking the dial on the stretching machine up to a very high level when the chiropractor is out of the room and almost stretching Bond to death. Luckily the chiropractor returns in time to save him but the incident confirms to Bond that Lippe has a great deal to hide, and he vows to get revenge, turning up the heat during the county's steam bath treatment to an almost unbearable level.
Ar the end of his stay at Shrublands, Bond feels fitter and more energetic than ever before and although pleased to be headed on assignment he is not pleased that his destination is the Bahamas, which he feels will be away from the main action. His mission is to work alongside a CIA agent to try to find two "kidnapped" atomic bombs that have been stolen by an organization of international terrorists called SPECTRE, led with an iron fist by international criminal and spy-for-hire Ernst Blofeld. Blofeld has sent a letter to the British Prime Minister and the President demanding money for the return of the bombs, otherwise they will be fired at two major targets and detonated. It is believed that the targets are a naval base in the Bahamas and the city of Miami. Bond is pleased to discover the CIA operative is none other than his old friend and espionage associate Felix Leiter. Felix is no happier about the vacation-style trip than Bond but the two men nevertheless start working with the local law enforcement to try to identify any visitors to the islands who might be the group they are searching for.
A man named Largo could be the leader of the group they are looking for; on the face of it the wealthy Italian playboy is in town on his yacht, the Disco, with a large group of men said to be participating in the annual underwater treasure hunt among the wrecks. Bond manages to get aboard the yacht by pretending to be interested in purchasing the beachfront home Largo has been renting and also attends the casino when Largo is there, winning Largo's money and momentarily getting a reaction out of him by using the word "SPECTRE" in a sentence, although Largo brushes it off and decides Bond is using the word and not the acronym. Bond has also deliberately started a relationship with Domino Vittalu who travels with Largo. He realizes, on learning her real name is Petruchi, that her brother was the expert pilot paid by Largo to hijack the plane carrying the bombs, and that he was killed on Largo's orders.
Bond and Felix had no luck finding the bombs on the Disco despite having with them a Geiger counter cleverly disguised as a camera. They decide to fly over the outlying, uninhabited islands and they eventually spot what appears to be a tarpaulin that has been painted to look like the sandy floor of the ocean. They realize the bombs have been moved but Bond finds the pilot's identity bracelet and papers and keeps them for Domino. They now know that the attack is imminent and alert their respective countries. Felix calls in a submarine to assist in the operation and both the commanders and the seamen are keen and willing to help.
Largo has planned to transport the bombs under the ocean with his men swimming like a formation of geese alongside. Bond, unknowing of this, devises the same thing, supplying his team with stiletto knives that will quickly kill predatory fish or Largo's men. He is still unable to make certain that Largo has the bombs and so tells Domino about her brother's death on Largo's orders, hoping to convince her to be his spy on the Disco. She will be armed with Felix's fake camera and if the Geiger counter registers the presence of atomic activity she will alert Bond by going on deck and appearing to take a picture. She will stay out of sight if there's no bomb. She never reappears but this is because one of the SPECTRE members on the Disco finds her in the area where the operation is being planned and checks out the camera when she tries to look like she is taking photographs but forgets to remove the lens cap. Largo tortures her with cigar burns and ice burns but she tells him nothing.
Bond, Felixand their men begin the swim in their formation and once they reach the Disco find it appears to be deserted, but when Bond goes to the surface to get his bearings he sees a man's face wearing a scuba mask ahead of him and realizes they have come upon Largo's team. He gives the command to attack them from behind but discovers this is the worst plan they could have carries out as Largo and his men are wearing little motors that make them fast and almost impossible to catch. The naval team with Bond fights valiantly and eventually kills Largo's men, but not without injury and loss to the team's ranks also.
Bond sees Largo ahead guarding the bombs and the detonator; he goes after him but becomes trapped on the sea bed as Largo "stalks" him from higher in the water. A physical fight between them favors Largo as he is larger and more powerful with disproportionately huge hands. As he begins to overpower Bond he reels back suddenly and Bond looks up to see that despite her terrible injuries at Largo's hands, Domino escaped the Disco and in killing Largo has both saved Bond and avenged the death of her brother. The bomb is disabled, the mission a success on all counts but one; Ernst Blofeld, the mastermind behind the ransom and the terrorist organization SPECTRE, escaped capture, and is still at large.
