The world watches in terror as billions of tentacles emerge from the anomaly. The tentacles begin to attack planets across the Universe. Zap leads a military strike against it via joystick while he sits safely at an Appleby's on Earth. As the tentacles approach Earth, Professors Farnsworth and Wernstrom argue whether to protect earth with a sphere of diamondium or diamondillium. They resolve the dispute with another round of Deathball, and Wernstrom's diamondillum sphere is constructed, encircling the planet. At the League of Robots, Bender wonders why they never make any plans to kill all humans, like their motto says. Calculon laughs at his idealism: the League hasn't killed a human in over 800 years, and that was a very sick girl scout.

The diamondillium sphere is completed just as the tentacles reach Earth… and they smash right through it. The largest tentacle extrudes something: it's Fry, a tentacle joined to him by the back of the neck. Fry addresses the world's population, saying he's found the reason for existence: "Thou shalt love the Tentacle!" People the world over are taken over by tentacles affixing themselves to the backs of their necks. The Planet Express crew — except for Zoidberg, who is caught — takes refuge in the Planet Express building. Fry knocks on the window, and says not to be afraid of the Tentacle. He's not brainwashed; he's just been fitting his diction to the importance of what he's saying. The Tentacle has loved us all from afar since we were amoebas; only now that the rift has been opened can it express its love. The Professors find that the Tentacle is made of "electromatter: matter's bad-ass grandma." Nothing from our universe can cut through it. Bender, disillusioned with the League, becomes further depressed when Fry no longer has time to talk to him because he's too busy being Pope of his new religion. Indeed, Fry has begun to dress in papal robes.

The news reports that only a few isolated pockets of resistance remain. One of those pockets is at Planet Express, but the Tentacle begins to find ways in: through the coffee maker, through the toilet. Farnsworth invents a neck protector, which looks at first like a metal plate, but is actually made from cardboard toilet-paper tubes. The Tentacle gets everybody but Leela and Amy. They hide out in an alley next to a dumpster in which Zap Brannigan is hiding. Hermes finds the three of them, and tells them to surrender and become part of something bigger than themselves.

At Fry's church he exults as the police bring a still tentacle-free Colleen to him. She admits that Fry wasn't enough for her; no one man is. If his ego can't take that, then he doesn't deserve to be Tentacle Pope of anything. Fry surprises her by agreeing. Why should she be satisfied with one man when love needs to share itself with the whole universe? She's moved; then terrified as a tentacle takes her by the neck; and then calm as she realizes that she does love the Tentacle. They embrace… along with all of Colleen's other boyfriends. There's enough love for everybody.

Leela, Amy, and Zap flee through the city and become trapped in an alley, where they run into Bender. They beg him for a place to hide. He opens a hatch; they pile inside what turns out to be a giant robot from the League, who is unaware of the humans inside; just that his leg feels funny. At a League meeting Bender goes on about how disgusting humans are. The hatch falls open, and Leela, Amy, and Zap fall out onto the floor. Bender claims not to know them, and not-so-surreptitiously points them to the exit while pretending to chase them. Calculon sees through the subterfuge, and laughs, telling him that to err is... human. Bender, affronted, challenges Calculon to a duel.

Leela, Amy, and Fry find the abandoned cabin of a soup bootlegger from the days of soup prohibition, well-stocked with bathtub minestrone. That night, as Amy cries over Kif, Zap commiserates: he misses Kif too. It's a ploy to seduce Amy. The next morning Leela finds them in bed together, but that's not what she's surprised by: it's the tentacles hovering over them. Zap and Amy are taken over. Another tentacle attacks Leela; she ducks, and it ties itself up in a knot, managing to choke and cut off its tip. Leela takes the tip, and sneaks into the Planet Express laboratory, where she makes a shocking discovery. Then Farnsworth discovers her, and many tentacles swarm at her.

At Fry's church, Fry says the Tentacle is about to address the world. Leela arrives, a tentacle in her neck. At the gathering Fry reveals that the Tentacle's name is Yivo. Yivo extrudes shlimself (shlee is without gender, though shlee sounds distinctly male, so for narrative purposes we'll stick with "him" from now on) through Fry's mouth, a talking tentacle. Yivo is the only being in his universe; he was alone for a trillion years until he saw the big bang, and realized that he was lonely. When their emissary, Fry, arrived, Yivo saw that he was also lonely... and so he reached into our universe so that we might feel each other's touch. Suddenly Leela springs into action, kicking Yivo and Fry aside; the "tentacle" on her neck was actually a purple garden hose. She has shocking news: Yivo may talk about love, but what he's actually doing is mating with everybody. These aren't tentacles: they're gentacles!