NOTE: This spoiler was submitted by Jeremy
The film starts in Mexico City during a Day of the Dead parade. A man in a white suit and skull mask walks by, while another man in a skull costume spots him and starts walking into a hotel with a woman. The couple enter their room for some intimacy. The man is 007/James Bond (Daniel Craig). He leaves his lover in the room while he steps out onto the roof to walk with his gun toward the building next to it and aim at the man in white, whose name is Marco Sciarra (Alessandro Cremona). Bond overhears Sciarra and two other men talk about blowing up a stadium and inquiring about someone known as "The Pale King". Before Bond can make a move, the men spot him and shoot back, but Bond kills the two men before blowing up the bomb, which destroys part of the building and causes it to come crashing down onto the roof of Bond's building. He falls through the wreckage but walks out into the city to pursue Sciarra.
Bond follows his target through the parade as Sciarra calls for someone to meet him in the square. Sciarra goes to a descending helicopter and climbs in as Bond catches up and beats Sciarra's goons before jumping in the helicopter with him. As it takes off, Bond fights both Sciarra and the pilot. The helicopter flies dangerously close to the civilians as Bond tries to kill his target. He finally succeeds in kicking Sciarra out of the helicopter before throwing the pilot out as well. Bond takes control of the helicopter and flies it away. He then looks in his hand at something he pulled off of Sciarra's finger: a ring with an octopus symbol on it.
M (Ralph Fiennes) is not happy with the damage Bond has done, especially since he hasn't authority to be in Mexico. Bond tells M he was taking an overdue holiday and that his encounter with Sciarra was a coincidence. M officially grounds Bond. As Bond leaves, the new head of the Joint Intelligence Service, Max Denbigh (Andrew Scott), whom Bond starts referring to as C.
Bond runs into Moneypenny (Naomie Harris) and shows her the real reason he went after Sciarra: he was sent a tape from the previous M (Judi Dench) shortly after her death, instructing Bond to find Sciarra, kill him, and go to the funeral in Rome. Moneypenny also gives Bond a box of items recovered from Skyfall. Bond looks in the box and sees, among other things, a picture of a man and a boy, with a third person's face burnt out of the picture.
Bond rides around the river with Bill Tanner (Rory Kinnear) where they get a glimpse of the new JIS building. Tanner says that C's plan is to create "Nine Eyes", a program that will allow access to intelligence streams in nine countries and also putting the 00 program out of service. The men meet up with Q (Ben Whishaw), who gives Bond simply a watch, but Q suggests that the alarm is very loud. Bond later steals a custom Aston Martin made for 009.
Bond arrives in Rome for Sciarra's funeral. He encounters Sciarra's widow Lucia (Monica Belucci). At night, in her home, Lucia is nearly executed by two men until Bond shows up and gets them first. Despite knowing that Bond killed her husband, he still seduces her and learns of a criminal organization that Sciarra was part of.
Bond arrives at the hideout of this organization by using the octopus ring as entry. There, he encounters a large number of people discussing events in Marrakesh and Tunisia, as well as the planned bombing in Mexico. A man cloaked in shadows (Christoph Waltz) enters and oversees the meeting. They also mention The Pale King and plan to get rid of him. He calls upon a man to be the muscle in their plans, only for a much larger fellow, Mr. Hinx (Dave Bautista), to step in for consideration. Hinx slams the man's head on the table and squeezes his head until he dies before wiping the blood off his fingers with a handkerchief. The man in the shadows then sees Bond and refers to him by his name, saying it's been a while. Bond appears to recognize the man as well. One of the minions in the building nearly attacks Bond until he throws him over the balcony. Bond escapes as Hinx chases after him. Bond sees that the car has hardly any working gadgets except for a flamethrower, which he uses on Hinx's car before ejecting himself from the car and fleeing. Bond then contacts Moneypenny and asks for information regarding The Pale King and Franz Oberhauser, the man in the shadows.
Moneypenny informs Bond that The Pale King is really Mr. White (Jesper Christensen), while she learns that Oberhauser and his father were reported to have died in an avalanche. Bond locates White in Austria, where he lives alone in a dilapidated home, dying of thallium poisoning as a result of leaving the organization. Bond convinces White to tell him where to find his daughter, promising his former enemy that he will protect her. He slides White a gun, knowing he would prefer to end his suffering. White tells Bond to find her at a clinic where she works, and that she will lead him to L'Americain, which will in turn bring him back to Oberhauser. White then puts the gun under his chin and pulls the trigger.
Bond finds White's daughter, Dr. Madeleine Swann (Lea Seydoux). She asks him some test questions before he tells her that he watched her father kill himself. Madeleine orders him to leave and angrily walks away from Bond outside the building before she is captured by Hinx and his fellow goons. Bond takes a plane and chases the villains, eventually causing them to crash their cars before he rescues Madeleine, leaving only Hinx alive.
Bond brings Madeleine to meet with Q, who has done an analysis on the ring. It contains files which reveal that Bond's most recent enemies (White, Sciarra, Le Chiffre, Dominic Greene, and Raoul Silva) were all connected to Oberhauser, and that other organizations like Quantum were subsidiaries of this organization. Madeleine says that the organization's name is Spectre, and that L'Americain is not a person as Bond had originally believed, but a hotel in Morocco.
Meanwhile in London, M has learned that Bond has left the country against his orders. He must also deal with C initiating Nine Eyes, though the decision to launch it must be unanimous, and C has at least one detractor. The 00 program is also officially shut down.
Bond and Madeleine travel to Tangier and locate L'Americain. There, they find a stash of tapes and pictures kept by Mr. White that lead to the next clue in where to find Spectre.
The two board a train headed to Spectre's main hideout. As Bond and Madeleine sit together, they are interrupted by Mr. Hinx. Bond battles the gigantic man while Madeleine tries to get a good hit in. Bond throws a chain around Hinx's neck and hooks the chain onto a barrel that is connected to other barrels, causing Hinx to get pulled out the train by the neck. Bond then proceeds to seduce Madeleine.
They arrive at the Spectre facility in the desert. Oberhauser and his men find Bond and Madeleine, where Oberhauser states that he is the mastermind behind every painful event over the last few years of Bond's life. He brings up Vesper Lynd's death, as well as the last M's. He then pulls up a video of Bond's last meeting with White, showing him passing the gun to White before his death. It is also revealed that C works under Oberhauser, and Nine Eyes will give Spectre access to all the intelligence streams. Bond then gets knocked out by a thug.
Bond wakes up strapped in a chair, prepped for torture. Oberhauser tells Madeleine how his father looked after Bond after the death of his parents, and he was something of a brother to Bond until he faked his death in the avalanche. Now, he is no long Oberhauser, but really...Ernst Stavro BLOFELD (totally called it). Blofeld turns on little drills to go into Bond's head. Madeleine approaches him and admits her love for him. Bond slips her his watch and sets the timer. Knowing what's happening, she slides the watch toward Blofeld as it explodes and unlocks the torture chair. Bond and Madeleine escape as the facility explodes.
Bond returns to London to join Tanner, Q, and Moneypenny as C is arrested. Madeleine leaves Bond because she wants no part in the life he leads. The heroes are ambushed, and Bond is taken.
Bond is taken to the former MI6 building and quickly takes out his captors. He finds Blofeld, now blind in his right eye and sporting his trademark scar. Blofeld says that Madeleine is in the building, which is set to explode. Meanwhile, M and the others attempt to relocate C and stop Nine Eyes from launching. M finds C in his office and tricks the villain into officially disabling the program. C fights M and tries to shoot him, but M causes him to shoot the glass ceiling, throwing C off-balance and causing him to fall over the balcony to his death.
Bond finds Madeleine and escapes with her through the Thames as the building is destroyed. Blofeld is escaping on a helicopter, but Bond manages to shoot him down. Blofeld is apprehended by M while Bond leaves with Madeleine.
The film ends with Bond taking another custom car from Q to join Madeleine.