Homer is watching a TV show on athletes who have competed in marathons. Homer is inspired to start training for the Springfield Marathon when he discovers that the oldest person to win an Olympic marathon was 'roughly' his age.
Homer and co. arrive at the marathon where Marge checks if he has everything he needs. Chief Wiggum starts off the race with his gun and then everyone is off. Athletes competing include Comic Book Guy in a Flash costume, Smithers being whipped by his slave driver Burns and a dehydrated Homer who resembles Grampa.
As the race is drawing to a close, two foreign athletes are in front. As Bart disguises himself as an Italian athlete to win the marathon, Kent Brockman reveals the prize - a walking tour of Springfield. Bart comes out of an alley, with a Italian sweatshirt and a moustache on, he crosses the finish line first. As he is handed the prize, a bird flies along and steals his fake moustache. Everyone angrily suggests they should chase him to get the trophy back. He then spots a mysterious stranger offering him a way out of getting lynched by the furious mob.
While in the strangers car, Bart discovers that the name of his savior is L.T. Smash. When they return home, L.T. reveals that he is a record producer and that he wants a bad boy like Bart for a new boy band named the Party Posse. While Marge protests, Bart reminds her that he has always wanted to be a rock star and Homer informs her that he has always wanted to get rid of Bart. She caves in and ends up signing the contract.
L.T. later introduces Bart to the other members. These are Nelson Muntz, Milhouse Van Houten and (correctly guessed by Bart) Ralph Wiggum. As they demonstrate how good they are at singing they are revealed to be horrible. While they are singing L.T. uses a machine made by N.A.S.A. to enhance their singing voices. Their first gig is at their school. They sing a song called 'Silent G'. Afterwards when they are basking in their glory they are paid a visit by N*SYNC who are equally as thrilled to see them as the Party Posse is to see them.
When watching a music-video show, the family see Party Posse's new video called Drop Da Bomb. Lisa is puzzled as to why they keep repeating the words 'Yvan Eht Nioj'. Homer re-assures her that it is nothing but she still is suspicious. When she rewinds the tape she sees a navy poster featuring Uncle Sam flashes up on the screen. She then realises that if you play 'Yvan Eht Nioj' backwards you get 'Join The Navy'. When she pieces everything together she spots Otto getting on a naval reserves bus she questions his motives. When he tells her that he's joining the navy, Lisa informs him he's being brainwashed to which he replies "Yer, probably something like that. Yvan Eht Nioj", and proceeds to hop on the bus.
Lisa goes to L.T. and informs him that the government is putting subliminal messages in his songs. With help from him, Lisa figures out that is why the band was formed. When the family goes to a Party Posse concert, Lisa points out to her parents (who don't believe her) that the concerts on a naval ship. As they start singing 'Four years of Love', a sergent who is a rank above L.T. in the navy shows L.T. the cover of the next MAD magazine which insults their band. So the sergeant turns off the N.A.S.A. machine. L.T., in a rage, turns the ship on making the audience jump off it. Homer, who was in the bathroom at the time, is trapped on the ship with the band members and L.T. who has seemed to have gone crazy.
L.T. travels to New York where he informs the Party Posse that the target they have to destroy is actually MAD Magazine. When they ponder as to how to stop L.T. from blowing up the beloved magazine, they realize they need the ultimate 'chill-out' song. As soon as it's mentioned. N*SYNC comes in with it all planned. However they reason with N*SYNC as to how to dance to the song. As N*SYNC finish dancing, Milhouse and Nelson debate over the blend of the dance moves. But it's too late as L.T. fires the torpedoes at MAD. L.T. ends up getting arrested while the group members pine over the fact that they could have been on the cover of MAD.
The episode concludes with N*SYNC informing everyone that the US Naval cadets help keep us safe.