This template contains the plot outline for the first three acts of The Beast with a Billion Backs, which is the same as the plot of "5ACV07" (5ACV07). The content of this page is included on both of those articles to avoid the need to change the same content in two locations.
The tentacles begin to emerge from the other universe and attack people on Earth, and there is no stopping them, as they appear invulnerable to laser fire, thus proving a military barrier ineffective. Farnsworth and Wernstrom propose encasing the planet in a shield of an impenetrable material, though they argue over which one they should use: Farnsworth's diamondium or Wernstrom's diamondillium—a quick game of Deathball ends in Wernstrom's favor.
Meanwhile, as the League of Robots appear oblivious to everything that is transpiring, Bender openly wonders why they are not killing all humans. Calculon explains that this is simply not their purpose (despite the League's motto, "Kill All Humans!"), and believes that Bender is bluffing when he wishes to do so.
The shield is placed around Earth, but the tentacles manage to break through without any effort. They proceed to attack everyone, and no one can escape thanks to the shield. Fry has also returned to Earth with a tentacle attached to the back of his neck and, apparently brainwashed, he announces that he has discovered humanity's purpose in existence: to love the tentacle.
The tentacles begin attaching to the Earthican people in the backs of their necks, causing everyone to fall in love with them. The crew (except for Zoidberg) manages to escape to the Planet Express building. It turns out, however, that no one is actually brainwashed—Fry is truly in love with the tentacle, and the tentacle loves him. Turanga Leela, however, refuses to believe this, and attacks the tentacle with Farnsworth diamondium cannon, but it has no effect. They discover that the tentacles are made of electromatter, which can cut through any form of regular matter, thus explaining how Wernstrom's shield and Farnsworth's cannon are useless.
Bender begins to feel upset that he now believes the League of Robots has no real purpose, and that Fry is again preoccupied since the tentacled creature made him the pope of a religion that worships it. Fry begins spreading the influence of the tentacle religion to every corner of the world. The rest of the crew continues to resist, but Farnsworth is also captured by the tentacles.
Leela and Amy escape on Amy's party board as Hermes and Wernstrom are captured with Farnsworth. Eventually they, along with Zapp, become one of the very few "normal" people left on Earth. Colleen, meanwhile is brought before Fry, who appears to be becoming mad with power. Colleen rebukes Fry for having his ego get in the way of understanding how she loves more than one man, but is confused when Fry sympathizes her statement. Fry encourages Colleen to share her love with the whole universe and places a tentacle in the back of her neck, causing her to fall in love with it as well. The two end up getting back together.
Leela, Amy and Zapp find Bender and beg for his help; Bender helps them hide by placing them in a compartment in the Destructor's leg and proceeds to attend another meeting with the League of Robots. However, the three fall out of the compartment, and Bender helps them escape while denying any relationship to them. Calculon calls his bluff and Bender, his human-hating reputation ruined in the League, challenges Calculon to a duel.
The three reach an abandoned logo cabin where Amy, still unable to get over herself, continues to grieve Kif's death. Zapp consoles her by convincing her to sleep with him. The next morning, the tentacles capture them, leaving Leela the sole being in the universe still unattached to one. While attempting to entwine itself around Leela, a tentacle twists itself and cuts off its own tip. Leela grabs the piece and returns to the Planet Express building where she examines it, but when she does, she is ambushed by more tentacles. Leela appears to become attached to a tentacle, and its influence has been spread to every corner of the universe.
Fry addresses the universe all that the tentacled creature has told him: the creature's name is Yivo, who does not have any gender, and so it must be refered to as "shkle" instead of "he" or "she," and "shklim" or "shkler" instead of "him" or "her." Yivo then begins to speak, revealing that shkle had spent a trillion years in solitude before realizing that shkle was alone after witnessing the Big Bang. Then shkle met Fry who was also lonely, and they fell in love, so shkle decided to spread that love onto everyone. But then Leela intervenes; it turns out that the "tentacle" in her neck is really a garden hose, and addresses what she herself has learned about Yivo by examining the tentacle piece: the tentacles are actually "gentacles," and shkle is mating with everyone.
The episode ends with "To be continued."