Bond discovers that the Zorin oil-pumping station is pumping seawater into its pipelines instead of pumping oil out. He is informed by state geologist Stacey Sutton that such a procedure could trigger a major earthquake. In order to find out what is going on inside the Zorin mine, they don miners uniforms and hide inside a tram car. They sneak into a control room where Bond sees Zorin setting a detonator for 3600 seconds (one hour) and Stacey finds a scale model of Silicon Valley. From the indicators on the model, she is able to tell that Zorin is planning to blow up the four major fault lines under San Francisco and flood the entire Valley with seawater. Suddenly, Zorin enters the room, and Stacey and Bond are forced to escape through a window. May Day goes after them. As Stacey and Bond look for a way out of the mine, Zorin sets off a powder keg below the San Andreas lake which instantly floods the mines with seawater. Zorin and his assistant, Scarpine, shoot all the surviving workers. Bond and Stacey try to escape through a ventilator shaft; Stacey makes it but Bond, along with May Day, are sucked back by the rushing water. Zorin rejoins his cohorts at the top of the mine, and they escape in their airship. The water level in the mine begins to drop. May Day realizes that Zorin meant to kill her, too, and helps Bond retrieve the bomb from a descending shaft by lifting out him and the bomb with a platform rig. With only seconds to spare, they try to push bomb and detonator out of the mine on a tram car, but the handbrake slips. May Day hops on the car and holds down the handbrake while Bond gives it a push. As May Day rides the car out of the mine, Bond keeps telling her to jump, but she stays there, holding brake in the open position. "Get Zorin for me!" she shouts. She rides the car outside the mine and a few seconds later the bomb goes off, taking her with it.
Seeing that his plan has been foiled, Zorin swoops down and grabs Stacey. Bond grabs on to one of the mooring ropes and is carried out over the San Francisco Bay. Zorin attempts to knock him off the rope by crashing him into the Golden Gate Bridge, but Bond quickly grabs hold of the cables and ties the mooring rope to the bridge's framework, causing the airship to crash into the bridge. Stacey takes this opportunity to leap out of the airship joining Bond on the girders. Zorin goes after them, armed with an axe, and he and Bond have at each other, until Zorin loses his handhold and falls to his death below. Mortner/Glaub (Willoughby Gray) tries to blow up Bond with a bundle of dynamite, but Bond cuts the airship free with the axe, and the jerking causes Glaub to drop the dynamite inside the cabin. The dynamite goes off, and the airship explodes. Back in London, KGB General Gogol (Walter Gotell) wants to award Bond the Order of Lenin for saving Silicon Valley ("Where would Russian research be without out it?" he explains), but 007's whereabouts are unknown, until Q releases a remote control spy "dog" that roams through Stacey's house, eventually locating Bond and Stacey in the shower together. When M asks Q about Bond's status, Q replies, "He's cleaning up a few details."