Buffy, Xander and Willow walk to Buffy's house. Misinterpreting an odd situation, they find Joyce kissing a strange man. Joyce introduces her friend, Ted Buchanan, a salesman. He tells them that he has been seeing Joyce for quite some time now. He charms Willow and Xander with computer talk and cooking, respectively. Ted promises to make it up to Buffy for surprising her. Buffy becomes uncomfortable with Ted's 50's sitcom mannerisms; this is not calmed by Ted's offer of miniature golf.
That night, Buffy beats a vampire to an unusually bloody pulp before killing him, worrying Giles that something is troubling her. She refuses to divulge, but Giles secretly has a good idea of what is happening. Later that night, Buffy asks Angel for his take on things, while she tends to the hand wound he sustained recently. He says that her mother needs a man in her life, and she should give him the benefit of the doubt. She reluctantly complies with this idea.
The golf outing goes poorly, as Joyce has revealed Buffy's anti-social behavior. When Buffy cheats, Ted lectures and threatens her with a slapping out of sight of the others, but his cheerfulness comes back full force when rejoining the others.
Joyce doesn't believe this incident happened, claiming Ted thinks the world of her. Buffy recruits her friends to spy on Ted. Under an assumed name, Buffy talks her way into Ted's workspace. He has never missed a day of work, doesn't get sick and is getting engaged. Indeed, Ted has a picture of Joyce on his desk, but the part with Buffy is folded under.
At dinner, Ted denies the engagement, but confesses to Joyce that he has hopes they will. Buffy slips out for some slaying and on her return, finds Ted has read her diary. He threatens to tell Joyce about the 'Slayer' unless she toes the line. She defies him and is slapped. In the resulting brawl, Ted falls down the stairs; Joyce rushes to him but he doesn't respond when she calls his name. She checks his pulse, looks up at Buffy and says "You killed him."
The day after a talk with the cops, Buffy is in a haze of guilt. Willow, Xander and Cordelia dig deeper into Ted's life -- discovering Ted's cookies are drugged; Cordelia finds Ted has had four wives since 1957, all of whom have since "disappeared". That night, while Giles patrols, Jenny surprises him and apologizes for avoiding him. A vampire attacks and Jenny accidentally shoots Giles with a crossbow instead of the monster. Giles, only slightly injured, takes the shaft out of his own body and dusts the vampire.
Buffy again finds an unexpectedly reanimated Ted in her room; they fight again, and upon cutting him Buffy discovers that Ted is a robot. Ted knocks Buffy unconscious and escapes to find Joyce, but the damage he has sustained in the fight has left him erratic. Ted confronts an astonished Joyce, but as he malfunctions he reveals his true intentions; as Joyce resists, Ted becomes violent and knocks her out. Buffy then awakens, and knocks Ted out with a frying pan. Meanwhile, the Scooby Gang investigates Ted's bunker, decorated in 50's style; Xander finds Ted's previous four wives -- all dead. The next day, Joyce swears off men forever and says that from now on, the two Summers women shall be manless. Buffy suggests renting a chick flick.
The gang returns to school the next day, with Buffy cleared of all charges, and discussing their discoveries about Ted. Apparently, the real Ted Buchanan was a sickly and unsuccessful inventor in the 1950s whose wife left him. In desperation, he built a robot version of himself, "a better Ted", possibly to be the man he thought his wife should have. The robot then kidnapped Ted's wife and held her captive in his bunker until she died. The robot then sought out other women resembling Ted's dead wife and repeated the process again and again.
All seems to have returned to normalcy... with the exception of Giles and Ms. Calendar kissing in the library.