Homer and his family attend a church picnic. During the festivities, Homer joins Bart for a game of capture-the-flag. Bart devises a plan to trick the opposition by using Homer’s underwear as a decoy flag. As Bart runs past the guards, waving the underwear, Homer pops up from behind a rock, grabs the real flag and takes off running. As he approaches the line, Homer runs out of breath. Kids run up and tag Homer, then pelt him with deviled eggs.

Realizing he humiliated Bart in front of his friends, Homer decides to do something about his weight. He begins power-walking late at night, hoping to keep his goal a secret from his family. One evening, he stops by the Kwik-E-Mart for a snack. But instead of buying sweets, Homer choices a Power Sauce bar. Later, Homer happens upon an all-night gym. Inside, he is assisted by action superstar Rainer Wolfcastle, who shows Homer how to get the most out of the exercise machinery. Homer’s efforts at the gym catch the attention of his family, who note his toned physique. One day, two slick looking men, Brad and Neil, approach Wolfcastle with a promotion for Power Sauce bars. The pair attempt to convince the actor that climbing the most treacherous mountain in Springfield, the Murderhorn, would make for spectacular publicity. When Wolfcastle turns down the dangerous assignment, Bart volunteers Homer for the job.

As Homer begins packing for his journey, Grampa tells him that he once attempted to scale the summit with another man named McAllister. According to Grampa, McAllister disappeared when he headed for the top alone. Later, Brad and Neil hold a press conference, announcing that Homer will climb the mountain in the company of two Sherpas. Secretly, Brad and Neil instruct the guides to carry Homer up the mountain as he sleeps. As the Sherpas carry out their assignment, Homer awakens. He promptly fires the guides and announces his intention to climb the mountain alone. But as he makes his way upward, he realizes the last leg of the journey is a sheer spike of mountain. Defeated, he takes refuge inside a cave, where he discovers the body of Grampa’s climbing partner, McAllister. Homer pulls the Simpsons flag from his gear and pounds a pole into a ledge. The force of the blows causes the top of the mountain to break off. Homer realizes he now stands on the top of the mountain. Using McAllister’s frozen corpse as a sled, Homer streaks down the mountain to safety.