It begins with the Mermaid Man and Barnacle Boy theme song. After the narrator announces the name of the episode, "The Secret Meeting," Mermaid Man and Barnacle Boy are shown spying on the Dirty Bubble. He is taking a bus to Bikini Bottom. The two heroes decide to stop whatever evil he is doing. Then the scene cuts to the Dirty Bubble coming out of the bus, laughing, and Mermaid Man and Barnacle Boy watching. Then, Man Ray, Jumbo Shrimp, the Atomic Flounder, and Sinister Slug join him in his evil scheme. Mermaid Man and Barnacle Boy are worried about this team-up.
The Dirty Bubble welcomes the villains to the B.G.A.T.F.B.C., which shall be held at Motel Evil, April 3, at noon. Mermaid Man and Barnacle Boy discuss what to do. Mermaid Man acknowledges that they are out-manned, but they are one step ahead of the villains. He takes a shell and uses it as a phone. He asks for the "ocean's greatest heroes" and is told to hold.
The scene then shows the villains gathering around the building. They enter it to find two men in white coats sitting at a long table reserved for the villains. The Dirty Bubble says the two men have to leave. One man, who is really Mermaid Man, says he thought it was set aside for the International Justice League of Super Acquaintances. The Dirty Bubble demands to know what that is, and Mermaid Man takes off the white coat, revealing who he is, leaving the villains surprised. Mermaid Man introduces the villains to the I.J.L.S.A. First the Elastic Waistband is seen, then Professor Magma, followed by Miss Appear and the Pyrite Panderer. They begin to battle.
Barnacle Boy is touched by the Atomic Flounder, grows an evil arm, and is knocked out. The Dirty Bubble fires Man Ray out of his mouth towards the Elastic Waistband, who blocks by his stretching belly. Mermaid Man jumps over to the Evil Arm on Barnacle Boy, who taunts him. The Evil Arm forces Barnacle Boy to swing fists at Mermaid Man. The Elastic Waistband asks what they should do, and Mermaid Man jumps and swings on a chandelier and spins several times in mid-air. He jumps on Barnacle Boy's shoulder and starts wrestling with the Arm. It continues to taunt Mermaid Man, and he pulls Barnacle Boy past Professor Magma, using him as a shield, and attacks the Atomic Flounder, who collapses.
The Sinister Slug is seen crawling up a wall behind Mermaid Man and spits at him. He jumps out of the way and the glop lands on the Atomic Flounder. The slime from the Sinister Slug hardens and Mermaid Man makes the Evil Arm touch the flounder. It explodes and Barnacle Boy wakes up. Mermaid Man then uses the hairnet on the Pyrite Panderer as a net and gathers the villains in it. Mermaid Man demands to know what the villains' group name is, which turns out to be the Bad Guys All Together for Book Club.
The villains sneer, saying they cannot arrest them for reading. Mermaid Man confirms this and tells the audience that no one can arrest anyone for reading. The show ends and the credits are shown.
- For the lost episode transcript, see The Bad Guy Club for Villains/transcript.
- The team of I.J.L.S.A. look much different. Captain Magma is changed to Professor Magma and is just a pile of lava, Miss Appear looks similar to Wonder Woman and has color changes, and Elastic Waistband has the power to puff up and wears a different costume. The Quickster has also been replaced by the Pyrite Panderer.
- Mermaid Man also refers to the IJLSA as the International Justice Lodge of Super Acquaintances.
- The end credits of the episode have the same layout as the end credits in the SpongeBob SquarePants series with the show's crew members credited.