When Marge and Homer are in the mood for romance, they trick the kids into thinking they’re having an argument by faking a quarrel, recording it onto audiotape, and then playing it back. Marge accidentally hits the reverse button on the boom box, attracting Bart and Lisa’s attention. They peer into the bedroom, and are horrified by what they see. Later, at school, a traumatized Bart tries to steady his nerves by eating Milk Duds. Nelson happens by, and hands Bart and Milhouse invitations to his upcoming birthday party. Nelson expects all the kids to attend. Bart tells his classmates that Nelson can’t beat up everyone at school, so he convinces them to boycott the party. When Marge finds out what happened, she insists that Bart attend. Bart protests, saying that if he goes he’ll be the only one at the party. Bart loses the argument. Homer drops Bart off at Nelson’s house. Just as Bart predicted, he’s the only kid at the party. Nelson is convinced that some of the other invitees will show up, but Bart assures him it won’t happen. He suggests that Nelson have fun with him. A short time later Bart watches as Nelson busts open a piñata with his fists. The next morning Bart tells Lisa the party wasn’t as bad as he thought it was going to be. As they board the school bus Nelson announces that he saved a seat for his new best friend: Bart.

Bart tells Nelson he doesn’t have time for new friends, but Nelson won’t take “no” for an answer. Bart soon discovers that hanging around with Nelson does have its benefits: when Jimbo, Dolph, and Kearney come around and begin to pick on Bart, Nelson straightens them out. That night Marge tells Homer she’d like to finish the romantic encounter they had the other evening. Homer reacts with excitement. Before Homer can make his way to the bedroom, Lisa asks him to read her a goodnight story: Angelica Button and the Dragon King’s Trundle Bed. As Homer reads aloud from the book, he soon finds himself drawn into the story, even though Lisa’s interest wanes and she falls asleep. When Lisa wakes up, she tells Homer he can’t read the book on his own: they have to read it together. The next day Nelson gives Bart a present: a jagged vest much like his own. Bart is impressed. Soon after, his life begins to change. Suddenly Bart is respected by everyone at school. Meanwhile Homer can’t keep himself away from the Angelica Button book. He reads through to the very end, and discovers that a major character — the wizard Greystash — ends up dead. A sobbing Homer makes his way to Moe’s tavern, where he drowns his sorrows. Milhouse accuses Bart of being Nelson’s sidekick. Bart denies this is true. Milhouse challenges Bart to prove it by going kite-flying with him. As Bart and Milhouse fly their kites, a bitter Nelson looks on. Later Nelson confronts Bart when he shows up late for a rendezvous. Bart makes up a story to cover for his tardiness, but Nelson shows him photographs of his kite-flying adventures with Milhouse. When he’s called away by his mother, Nelson promises Bart he’ll deal with the situation later.

Bart tells Lisa he’s convinced that Nelson is going to do him bodily harm. At school Nelson pulls Bart into his locker for a talk. Nelson apologizes to Bart for freaking out on him earlier. Nelson asks Bart if they are still best friends. Bart tells Nelson he only became his friend because he felt sorry for him. Bart wants nothing more to do with Nelson. Nelson turns cold, and walks away. Meanwhile Lisa asks Homer to finish reading the Angela Button story. Homer doesn’t want to upset Lisa, so he concocts a happy ending of his own. After Homer leaves, Lisa pulls out another copy of the book and reads the real ending. She concludes that Homer’s was better. Bart goes on a field trip to the Springfield tide pools. He’s paired with Nelson. They make their way to a grotto, where Bart begs Nelson not to kill him. Instead of harming Bart, Nelson says Bart is a bad friend. Moments later the tide comes in, and the water rises over Bart and Nelson’s heads. Nelson grabs Bart and swims him to safety. On the beach Skinner performs mouth-to-mouth resuscitation on the unconscious Bart, reviving him. Bart thanks Nelson for saving his life. Nelson tells him their friendship is over.