After making it to the top of the charts, members of the Silver Boulders, a popular tween rock band, find themselves undermined by internal squabbling as the bandmates seek different creative directions.

Rosalina comes back after her music cruise, but Michel (the French guy Rosalina kissed on the cruise) also comes back, criticizes Nat's music, and kisses Rosalina which Nat sees. This causes a heated fight between Nat and Rosalina in which they break up and Rosalina quits the band.

The Naked Brothers Band and another band, the L.A. Surfers, find themselves competing in a "Battle of the Bands" charity event benefiting Little Kids Rock. Rosalina starts to fall for the L.A. Surfers' lead singer, Bobby Love. It annoys Nat that Rosalina hangs out with the opponent's lead singer. It turns out that Bobby is just dating Rosalina to get to Nat and is lying about everything, i.e, his British accent, not writing his own songs, etc. Nat and Bobby fight and declare at a press conference that the charity event is now a competition and the losing band's proceeds from their next CD goes to the charity.

The band's next concert stop is in New Orleans where Nat reunites with a childhood friend, sending Rosalina into a jealous frenzy! Meanwhile, Alex initiates an extreme environmental movement to help save polar bears at the North Pole, but devious reporters frame him to appear as a conceited rock star who hates Santa!