SpongeBob and Patrick are upset, because Sandy has gone to Texas for two whole days, they decide to throw her a welcome home party. During their party, SpongeBob and Patrick notice that Sandy is scratching and biting her fur. Sandy explains that upon her return from a science convention in Texas, she unknowingly brings back a flea. Sandy asks SpongeBob to open her briefcase and take out the flea collar. The flea jumps out of her fur and lands on SpongeBob. SpongeBob gets bitten and grabs the collar. The flea then lands on Patrick and bites him, causing Patrick to take the collar. They fight over the collar, then Sandy grabs the collar and wraps it around all three of them. The flea then reproduces, causing the flea collar to be eaten away, rending it useless. Fleas take over Sandy's treedome, and no one can escape the dome. Patrick blames SpongeBob for throwing the party and getting infected, then blames Sandy for bringing the flea. SpongeBob states they may be living in a sea of fleas instead of salt water, thus giving Sandy an idea on how to get rid of the fleas. Sandy was unique crashing into the cauldron with fleas by infecting all their space in the dome with saltwater, but all the Bikini Bottom citizens are stuck in the dome at the end.
( ‣ ) Associated production music
( • ) Original music
( ◦ ) SpongeBob music
• ? - Sage Guyton, Jeremy Wakefield [title card/SpongeBob crying] • ? - Jeremy Wakefield [Squidward gardening] ‣Main Street - Alec Gould [SpongeBob and Patrick preparing for Sandy's arrival] • ? - Nicolas Carr ["Welcome home Sandy, you know that we missed ya..."] • ? - Sage Guyton, Jeremy Wakefield [Sandy scratching herself] • ? - Nicolas Carr ["You ready?"] ‣Drama Link (b) - Hubert Clifford [flea biting Sandy] • ? - Sage Guyton, Jeremy Wakefield [Sandy explains what a flea is] ‣Bach's Toccata - Johann Sebastian Bach, Peter Lea-Cox ["I'm gonna turn into a vampire!"] ‣Six Powerful Cues (d) - Wilfred William Burns [Patrick takes the flea collar] •Chase Cue 1 - Sage Guyton, Jeremy Wakefield [they fight over the collar] ‣The Creature A - Gregor F. Narholz [fleas multiplying] ‣House of Horror - Larry Hochman [fleas biting SpongeBob, Patrick and Sandy] •Squiddy G - Nicolas Carr, Barry Anthony [plays on Squidward's headphones] •Chase Cue 2 - Sage Guyton, Jeremy Wakefield [Sandy stepping on fleas] ‣Drama Link (d) - Hubert Clifford [SpongeBob screams] ‣Big Bad Giant - Paddy Kingsland ["Okay, you know what?"] ‣Tympup A - Sammy Burdson, John Charles Fiddy ["I do not play games."] • ? - Nicolas Carr ["I do not play games."] ‣They're Coming! - Trevor Duncan [they hide in the treehouse] ‣ ? [Sandy gets an idea] ‣West Side Rumble - Sam Spence [fleas washed away] • ? - Sage Guyton, Jeremy Wakefield [ending]