The episode begins at the Garage, where the legendary rock band, KISS, is performing in front of a live audience. Among the audience members are Thundergirl and Meltman. Thundergirl has a hard time believing that Meltman was able to get tickets for the concert. Meltman tells her that he knows KISS, as they used to jam together in high school. He tries to get into the concert, but the Usher launches him out. Meanwhile, the noise of the concert awakens a cranky Big Baby, who has been sleeping in a toy chest.
At Action League Headquarters, The Flesh and Stinky Diver are dancing to KISS' music on the radio. The Flesh then bangs his head up against Stinky's, causing it to fall off his body. Suddenly, they hear and see Big Baby as he approaches them. Big Baby steps on Stinky's head as he walks towards a train set, destroying anything in his path. As Stinky puts his head on, he realizes that Big Baby is heading for the Garage. He and The Flesh board the Action Mobile and chase after him.
Back at the concert, Kiss continues playing as Big Baby knocks down the door. He is mad, and plans to stop the concert so he can go back to sleep. KISS stops, and while they don't remember Big Baby being part of the show, they claim to like it. Big Baby then tosses a speaker, which lands on Meltman, but Thundergirl flies out of the way just in time. She laughs at Meltman's misfortune, saying it serves him right, then Big Baby swats her, causing her to land in the Action Mobile, which is on its way to the Garage. This causes Stinky to lose control of it and drive into the road, where they all get flattened by a steamroller.
Back at the concert, it looks like Big Baby is about to get his way, as he picks up one of the KISS members and teethes on it. The narrator asks the viewers if this concert will be KISS' final, then tells them to stay tunes for Part 2.
In the second act, just as it looks like KISS is done for, Meltman rises from the speaker and plays "Rock-a-Bye-Baby" on an electric guitar to calm Big Baby. This plan works, as Big Baby releases the Member of KISS and falls asleep. With Big Baby asleep, KISS is now able to continue their concert. All four members of the Action League dance along, and Stinky accidentally shoots his spear gun into the air. This causes the studio to fall on top of them as the episode ends.
- This episode marks the first of two appearances of Big Baby.
- This episode aired in theaters before the movie, Good Burger.