Somewhere in England, far away from the Village, Agent Potter is working as a scorekeeper at a cricket match. He uses a pair of binoculars to watch an attractive female spectator wearing a white dress. He then watches the bowler, fellow agent Colonel Hawkes, who is just short of making a century. Hawkes knocks the ball into the woods and the woman slips away and replaces his ball with her own special one. As Hawkes goes for his next swing, the ball explodes.
Mr. X, an English agent who looks like Number Six, reads about Hawkes' death and meets with Potter, now disguised as a shoeshine man. Potter explains that Hawkes was tracking down Dr. Schnipps, a mad scientist with a super rocket he plans to launch at London. Potter informs Mr. X that he'll be following on where Hawkes left off, and gets a message telling Mr. X to go to a record store. As Mr. X leaves, the woman watches from a department store window, posing as a mannequin.
Mr. X listens to a special record at the record store's listening booth, giving him his mission. Mr. X goes to the cricket field and enters the match, working his way up to a century. The woman is watching and again slips her ball in for a stray ball. Mr. X spots the substitution and catches the ball and throws it into the woods, rather than hitting it. It explodes at a safe distance and he goes after the woman, only to find a handkerchief saying to meet her at the local pub.
At the pub, Mr. X doesn't spot the woman, and orders his usual. As he drinks he notices a message on the bottom of the glass. When he finishes it he can read it: "you have just been poisoned." He quickly orders a series of drinks and gulps them down in rapid succession, then runs to the restroom to throw up. Inside, he pulls down a towel with a message suggesting he go to the nearby Turkish baths. Once there, the woman emerges from another cabinet and places a transparent dome on his head and runs a broomstick through the door handle. He kicks himself free and finds another message inside the woman's cabinet, directing him to a boxing booth.
Mr. X goes to the boxing booth, unaware that the woman is disguised as an old woman. The announcer presents the champion, Killer Komanski, and introduces Mr. X as his opponent. Mr. X is ushered into the ring and as they fight, Komanski tells Mr. X to go to the Tunnel of Love and then knocks him to the floor. Mr. X rides in the boat and the woman addresses him from behind, saying she loves him and thinks he's a worthy opponent for her. She congratulates him on passing her first tests and says they'll meet again. He turns to find she's slipped a transmitter onto the rear seat. He throws it over the side where it explodes harmlessly.
Going outside, Mr. X follows the woman through the carnival but is always one step behind. He finally spots her leaving in a car and takes another car in pursuit. As he drives through the countryside, she taunts him over the radio, and then causes the road to twirl just by spinning her finger. Finally she goes to ground in an abandoned town. Mr. X spots three stores: a candlestick maker, a baker, and a butcher. The woman taunts him over the loudspeakers, saying she's Death. Her father Schnipps would be there but he's busy with his super rocket.
Mr. X smashes into the butcher store following the sound of her voice, but finds an automatic machinegun waiting for him. He crawls under its arc of fire and disables it, then takes the gun and goes after her in the next store. He opens fire only to discover a dummy. A trap door opens beneath him and he manages to use the gun to catch the edges. He dangles over a bed of spikes, which start to rise as Death tells him that they're electrified. Thinking quickly, Mr. X pulls over a wooden shelf and drops it beneath his feat, insulating himself from the current and the spikes.
Climbing back up, Death warns Mr. X that the floor is mined and no matter what he does, they'll all explode in 90 seconds. He swings across the floor on a burning steam pipe and lands in the candlestick maker's store. There are racks of candles burning everywhere. Death tells him that they are made with a cyanide derivative. He runs for the doors but metal shutters smash down. Mr. X starts to blow out a candle but Death warns him that they'll explode if they're put out. With time running out, he moves several of the racks near a shutter and uses a bellows to blow them out from a safe distance, blasting the shutter down.
As he goes out onto the street, Death opens fire on him from a tower. He takes refuge in a garage while she expresses her admiration for him for surviving her traps. She invites him to join forces with her and her father, but Mr. X starts up a bulldozer and exits the garage, using the blade as a shield. Death uses a mortar rifle and then grenades. When the bulldozer grinds to a stop, she fires a bazooka at it, blasting it to bits. Satisfied that Mr. X is dead, she goes to her waiting helicopter. However, Mr. X hides in the sewers at the last minute. He follows her and holds on to the bottom of the helicopter as she flies to meet Schnipps.
Death lands near a lighthouse and takes a secret underground passageway there. Mr. X follows and enters Schnipps' headquarters, where he has portraits of Napoleon and Josephine displayed everywhere. Mr. X knocks out one of Schnipps' henchmen, dressed as a Napoleonic marshal, and takes his uniform.
Upstairs, Schnipps greets Death, who is his daughter Sofia. Sofia insists that she disposed of Mr. X and Schnipps reviews his men, promising them shares of London once he has conquered it.
Below, Mr. X knocks out another henchman and sabotages the rifles in the armory. He also rigs the grenades by putting the explosive in the handles. Above, Sofia and her father prepare to start the super rocket's countdown and prepare to leave by sea. Schnipps notices his missing henchmen and sends the rest down to investigate. Mr. X pretends to be a missing henchman and catches them off guard, then runs for the boat. He stops, daring the men to shoot him. They pick up the sabotaged rifles and open fire, and are killed by the backfire. However, when Mr. X climbs up to the control room, he finds Sofia waiting for him with her own gun. She ties him up and he realises that the lighthouse is the rocket. Sofia and Schnipps start the countdown and go downstairs to get Schnipps' papers. Mr. X frees himself, sabotages the controls, and then uses he rope to climb down the side of the lighthouse. He gets to the boat and prepares to make his escape. Sofia and Schnipps spot him and throw grenades... and realise the explosives are in the handle. The grenades blow up, killing father and daughter and destroying the lighthouse.
In the Village Nursery, Number Six closes the storybook as he concludes his story of the time he saved London. He tells the three children that he'll tell them another story tomorrow and puts them to bed. Number Two, who looks suspiciously like Schnipps, is watching from his office and furious that the plan to get Number Six to slip up and reveal something around the children didn't work. His assistant, who looks suspiciously like Sofia, admits it was a good try. On the monitor, Number Six looks up and wishes everyone watching him a good night.