SpongeBob and Patrick blow bubbles, but they soon get bored. SpongeBob suggests they "spice up" their bubble blowing. Patrick is struck with an idea and takes out a bottle of hot sauce. He dunks his bubble wand into the bottle and blows a spicy bubble into SpongeBob's eyes. SpongeBob screams as his eyes glow red and disintegrate, then grow back. Then, he blows a spicy bubble into Patrick's eyes, doing the same thing to him. Patrick wonders if hot sauce is bad for their eyes. Then, they said "Nah," and laugh. They burn each other's eyes repeatedly, and the effect goes again. Meanwhile, in his house, Squidward is clipping his likeness into a bonsai of himself. Just as he is about to clip off a straggler leaf, they scream, and he lops off the entire head. The beheaded bonsai requests that Squidward avenges it. Squidward angrily yells at them out the window, but SpongeBob blows a big spicy bubble, and it popped next to him, burning him to ashes and crippled him.
SpongeBob and Patrick go to Sandy's treedome, where she is outside fixing an airtank. They tell her about their new discovery, with Patrick convinced he is a genius for his new idea, even thinking he is smarter than Sandy. She tells them she is busy fixing a clog in the airtank. Patrick suggests she breathes water like a "smart person," and she explains land creatures need air. Patrick simply dismisses her as stupid. SpongeBob tries to help clear the blockage by blowing spicy bubbles onto the airtank, but it melts. Water rushes into the treedome, filling it completely. Sandy only has a little bit of air left in her suit, so she goes to her submarine which has enough air to go to the surface and replenish the air supply for her treedome. However, SpongeBob opens the door and water rushes in. Sandy tasks SpongeBob with driving the submarine to the surface, as the low amount of air is making her woozy. As they make their way to the surface, the lack of air in Sandy's suit causes her to act crazy and hallucinate and doing crazy things such as licking Patrick, seeing atoms and thinking she has spider-webs on her face. When they reach the surface, a delirious Sandy suddenly gets a craving for a Krabby Patty and drives the submarine through the roof of The Krusty Krab. Her suit's air supply is finally depleted, and she removes her helmet. She takes a patron's Krabby Patty and eats it, but its later spat out by SpongeBob pulling her tail, and Mr. Krabs appears, wanting to know what was going on, and SpongeBob explains everything.
SpongeBob and Patrick try to help Sandy get air, and they notice air bubbles from the submarine on the ceiling. SpongeBob uses a line of straws to reach them. Patrick sucks them in, then blows into Sandy's mouth. SpongeBob suggests Mr. Krabs might have air in him, telling him Squidward says he is "full of hot air" (which Squidward nervously denies). Mr. Krabs says he indeed has an air bubble or two and pulls in his eyestalks so Sandy can breathe them in. Pearl comes in and SpongeBob suggests she could help give air to Sandy, because she is a mammal, just like Sandy. Pearl agrees, saying "I guess we mammals gotta stick together." Sandy puts her mouth over Pearl's blowhole, and Pearl exhales, inflating her like a balloon. SpongeBob figures he can go to the surface and fill a bubble with air. Using an oxygen tank (which neither of them realizes could be used to help Sandy), he rockets to the surface, covers himself with bubble soap and inhales to create a giant air-filled bubble, then he puts it into the treedome.
Sandy wakes up in the treedome with SpongeBob and Patrick. SpongeBob explains that he saved her with bubbles and she remembers that it were bubbles which caused all the trouble in the first place. Sandy tells them not to blow bubbles around her treedome anymore, but it turns out SpongeBob already blew one giant bubble around the treedome, which lifts it away.
Despite Squidward calling his trimmed plant a bonsai, it is, in fact, a topiary. A bonsai is a miniaturized tree, while a topiary is a shrub, bush, or tree trimmed in a certain shape (in this case, Squidward's head).
This is the second time Sandy needed more than just an air helmet to breathe. She attempted (unsuccessfully) to use a pickle jar as a makeshift helmet in "Pressure."
For some reason, Mediacom and some other TV services list this episode as "Bubble Trouble."