The episode begins at the Refrigerator Museum of Art as the Narrator tells the viewers that a thief has been stealing paintings right out from under their magnets. The Curator tells The Flesh, Stinky Diver, and Meltman that he's glad they're here to help him guard the latest Timmy original painting, My Techer. If anything bad happens to it, they'll have to cancel the big opening tomorrow. Stinky assures him that The Action League is on the job. As The Curator Leaves, Stinky tells Meltman he's honored to guard the painting. Meltman tells Stinky that he loves Timmy's use of color to redefine space. The Flesh tells Meltman and Stinky that he likes the purple shoes. Thundergirl, who is painting, doesn't believe The Flesh, Stinky, and Meltman know anything about art. The Flesh walks up to her, and tells Stinky and Meltman that she made an exact replica of My Techer. As Stinky and Meltman walk up to the replica, His Dishonor, The Mayor is behind them, unseen. While they are distracted by looking at the replica (with Stinky expressing his disgust for it), The Mayor steals My Techer. Thundergirl tells Stinky that art was her best subject in school, but Stinky doesn't believe her. They turn around, and are shocked to find out the "My Techer" painting has been stolen.
The Refrigerator Museum of Art has now been blocked off with police tape as The Chief is not happy with the League for messing up their guard duties. He knows they'll be in a lot of trouble if they don't get My Techer back in time for the grand opening tomorrow. He has an idea on how to get it back.
Moments later, the League stow away inside a sculpture by the renowned artist, Terra Cata. As The Flesh, Thundergirl, and Stinky try to squeeze inside, Meltman asks The Chief how this plan will help them get the painting back. The Chief explains that when the art thief steals the Terra Cata sculpture, he will unwittingly take them to where My Techer is being held. He then tells him and the rest of the League to make room, as he jumps inside.
Later that evening, The League's operation is threatened by an unforeseen development; Meltman tells the rest of the League that he has to go to the bathroom. As The Flesh, Thundergirl, and Meltman express their disgust, The Chief tells Meltman to hold it in. Suddenly, they hear someone coming. The Mayor has arrived, and is using a crane to load the Terra Cata sculpture into the back of his truck. The League is having an uncomfortable ride, and due to their weight, it's not easy for The Mayor to properly load the Terra Cata sculpture. Eventually, he manages to get it into the back of his truck.
With his heist a success, The Mayor decides to head back to his mansion to add the Terra Cata Sculpture to his personal art collection. As he starts his truck up, he accidentally causes the Terra Cata sculpture to fall off it, leaving it behind as a result. He is not happy with this outcome.
The next morning, The Mayor is sitting in his rocking chair next to My Techer painting. The League awakens, and Thundergirl tells them that she can see the painting on the table. The Mayor walks up to My Techer and boasts about how only he can look at it. Meltman tells The Mayor that his evil plan will soon be foiled as he and the rest of the league push the Terra Cata sculpture to the edge of the table, breaking it as a result, but also freeing them. The Mayor is not happy that the Action League stowed away in his stolen art. The Chief tells The Mayor he's under arrest for art theft, but The Mayor is now holding up the painting. He reveals he is standing atop a large paper shredder. One false move, and he will drop My Techer into the shredder. The Narrator asks the viewers if the Action League will be able to stop The Mayor from shredding the painting, then tells them to stay tuned for Part 2.
In the second act, Stinky Diver tells The Chief that one clean shot from his spear gun is all he needs to stop The Mayor and save My Techer. The Chief approves the plan, but tells him to aim carefully, as the entire art world is depending on him. The Mayor tells Stinky he doesn't have the guts. Stinky shoots, but his shot accidentally goes through the painting. He tries again, and misses again, making another hole in the painting. He tries once more, and this time, is determined not to miss. He hits The Mayor as planned, knocking both him and the My Techer painting into the shredder. The Chief is horrified at the state of the shredded painting and asks the League what they're going to do about it now.
Later that day at the Grand Opening, it is revealed that Thundergirl's replica of My Techer was used to replace the original. The Curator thanks The Chief for taking such good care of the painting. The Chief tells him it was no problem. Stinky tells Thundergirl that he, The Flesh, and Meltman owe her an apology. Meltman tells her that her replica saved their hides. The Flesh tells her that he likes the way she used color to redefine space. He sniffs, then leaves to find a delicious snack to eat. Thundergirl thanks them, and tells her that her replica is pretty good. Suddenly, The Flesh is near a plate of hot dogs and is holding a bottle of mustard. He tries to squirt the mustard onto the hot dogs, but accidentally squirts it all over Thundergirl's replica. The Curator, The Chief, Thundergirl, Stinky, and Meltman all stare angrily at The Flesh, who nervously says, "Oopsies!" as the episode ends.
- Stinky Diver: "It's an honor to guard such a brilliant painting."
- Meltman: "I love Timmy's use of color to redefine space."
- The Flesh: "I like the shoes. They're purple!"
- Thundergirl: "Ah, what do you Philistines know about art?"
- Stinky Diver: "One clean shot, Chief. One clean shot is all I need."
- The Chief: "Okay, but don't miss! The entire art world is depending on you!"
- The Mayor: "Ha ha! You don't have the guts! This painting's worth millions!"
- (Stinky shoots a hole through the "My Techer" painting")
- The Mayor: "Make that thousands."
- (Stinky shoots another hole through the "My Techer" painting)
- The Mayor: "Uh, try pennies."
- The Chief (after the "My Techer" painting is shredded): "Blast it! That painting's more shredded than a box of shredded wheat in a... shredder! What are we gonna do now?!?"
- The "Terra Cata" sculpture is really a Chia Pet.