American NASA spacecraft Jupiter 16 is hijacked from orbit by an unidentified spaceship. The United States suspect it to be the work of the Soviets, but the British suspect Japanese involvement since the spacecraft landed in the Sea of Japan. To investigate, MI6 operative James Bond is sent to Tokyo after faking his own death in Hong Kong and being buried at sea from HMS Tenby (F65).
Upon his arrival, Bond meets a mysterious Japanese woman while watching sumo. She introduces Bond to local MI6 operative Dikko Henderson. Henderson claims to have critical evidence about the rogue craft, but is killed before he can elaborate. Bond chases and kills the assailant, taking the assailant's clothing as a disguise and escapes in the getaway car, which goes to Osato Chemicals. Once there, Bond subdues the driver and breaks into the office safe of president Mr. Osato. After obtaining certain documents, Bond is pursued by armed security, but is rescued by the woman he had met earlier, who flees to a secluded subway station. Bond chases her, but falls down a trap door leading to the office of the head of the Japanese secret service, Tiger Tanaka. Tanaka reveals that the woman is his assistant Aki. The stolen documents are examined and found to include a photograph of the cargo ship Ning-Po with a microdot message saying the tourist who took the photo was killed as a security precaution. While at Tanaka's spa, Bond meets with Aki again and they spend the night together.
Bond goes to Osato Chemicals to meet Mr. Osato himself, masquerading as a potential new buyer. Osato humours Bond, but after their meeting he orders his secretary, Helga Brandt, to have him killed. Outside the building, assassins open fire on Bond before Aki rescues him again. Bond and Aki drive to Kobe, where the Ning-Po is docked. They investigate the company's dock facilities and discover that the ship was delivering elements for rocket fuel. They are discovered, but Bond eludes the henchmen until Aki gets away; however, Bond is captured. He wakes, tied up in SPECTRE operative Helga Brandt's cabin on the Ning-Po. In a sexy cocktail dress, she interrogates Bond, but he thinks of managing to bribe his way to freedom when she suddenly chooses to enjoy herself by kissing and freeing him in order to have sex. Brandt flies Bond to Tokyo the next day, but en route she sets off a flare in the plane and bails out, finally persuaded to kill him. Bond manages to land the plane.
After finding out where the Ning-Po unloaded, Bond flies over the area in a heavily armed autogyro created by Q. Near a volcano Bond is attacked by helicopters, which he defeats, confirming his suspicions that the enemy's base is nearby. A Soviet spacecraft is then captured in orbit by another unidentified craft, heightening tensions between Russia and the United States. The mysterious spaceship lands in an extensive base hidden inside the volcano. It soon turns out that the true mastermind behind this is Ernst Stavro Blofeld, the mysterious leader of SPECTRE who has been hired by the People's Republic of China to start a Soviet-American war. Blofeld summons Osato for not having killed Bond, who immediately blames his assistant, Brandt. Blofeld then gives Osato a last chance, but as Brandt leaves, he activates a mechanism that drops her into a pool filled with piranhas. Brandt is forced to pay for her failure with her life by being devoured alive, and Blofeld instructs Osato to kill Bond.
Bond is then informed of Tanaka's plan: he is to train with Tanaka's ninjas, disguise himself as a Japanese fisherman alongside a Japanese wife, and infiltrate SPECTRE's island. Before this plan can be completed, Aki is killed when she accidentally ingests poison that a SPECTRE assassin had meant for Bond to take. Bond quickly moves on and enters into a fake marriage to Tanaka's student, Kissy Suzuki. Acting on a lead from Suzuki, the pair reconnoitre a cave and the volcano above it. Establishing that the mouth of the volcano is a disguised hatch to the secret rocket base, Bond slips in, while Kissy goes to alert Tanaka. Bond locates and frees the captured astronauts and, with their help, steals a space suit in an attempt to infiltrate the SPECTRE spacecraft "Bird One." However, Blofeld spots Bond, and he is detained while Bird One is launched; Bond is taken into the control room where he meets Blofeld face-to-face for the first time.
Bird One closes in on the American space capsule, and United States forces prepare to launch a nuclear attack on the USSR. Meanwhile, the Japanese ninjas approach the base's entrance, but are detected and fired upon. Bond manages to open the hatch, letting in the ninjas. During the ensuing battle, Bond fights his way to the control room, kills Blofeld's bodyguard Hans by flipping his body into the piranha pool, and activates Bird One's self-destruct before it reaches the American craft. The Americans stand down their forces.
Blofeld, who had earlier killed Osato to demonstrate the price of failure to Bond, activates the base's self-destruct system, a bomb that triggers a volcanic eruption and escapes. Bond, Kissy, Tanaka, and the surviving ninjas leave before the eruption destroys the base, and are picked up by the Japanese Maritime Forces and the British Secret Service.