Milo, Melissa, Zack and Mort must learn to overcome their own conflicting concerns in preparation for their first Battle of the Bands competition.
Milo, Melissa, Zack, and Mort enter a battle of the bands contest. Due to a misunderstanding, they are entered under the name Just Getting Started. As the rest of the band is getting set up, Zack is astonished to learn that his old band, now named The Lumbermaxes, is also taking part in the event. Despite claims to the contrary, Zack starts to feel a sense of rivalry with his former band, and then explains their history to his current band. Overcome with a desire to defeat The Lumbermaxes, Zack becomes hostile and demanding towards the members of Just Getting Started.
The contest soon takes off, with Scott and The Undergrounders and The Lumbermaxes performing initially in front of a group of judges that includes Slash. After trying to figure out how he can play all his bandmates' instruments and his own at once, Zack realizes that he's lost sight of what the group came there to do. Just Getting Started then performs and-despite a flooding parking lot and other Murphy's Law hazards-wins the contest. Max then tries to convince Zack to rejoin The Lumbermaxes but is refused.
Melissa, and again later Zack, worries Melissa's bass will go out of tune. It's kind of an inside joke as it is widely accepted basses don't go out of tune. (It could be she thinks her strings are old and can't afford a new set.)
There are several Phineas and Ferb extras in the audience such as, Pyramid Peggy, (with a different hair style) Momo (in blue instead of purple) and Jeremy's unnamed drummer.