At lunch, Gordo tries to get seats at the cheerleaders' table for Lizzie, Miranda and himself, but Kate and Claire run them off and they have to eat on the grass. What's worse, they have to watch the cheeleaders practice. While doing a pyramid formation, Kate falls off the top and dislocates her shoulder. The next day when she arrives at the lunch table with her arm in a sling, Claire coldly informs her that since she can't cheer, she's been voted off the squad and isn't allowed to sit with them. All of a sudden Kate is a social nobody, reduced to eating her lunch alone on the grass and banished to the "dork hall!"
Lizzie, Miranda and Gordo soon find out that life with Claire as the new "Queen B" at the school is much worse that it was with Kate at the top, so Lizzie convinces her friends to start a campaign to make Kate popular again. Their efforts don't work at first, so Lizzie tries another idea: make it possible for Kate to cheer once more. After convincing Kate to go along with the idea, Lizzie teaches her a variety of one-armed cartwheels and tumbles. Kate learns well but is her typical self and barely gives Lizzie a word of thanks. Kate then shows up at cheerleading practice and challenges Claire. After watching Kate do a series of spectacular tricks, Claire attempts a cartwheel and injures her wrist. The next day at lunch Claire is in the same situation as Kate was before, and she morosely heads for a table to sit by herself. Lizzie and her friends are disappointed that Kate didn't learn anything from her experience, but they're in for an amazing surprise when Kate goes over to Claire and offers to let her sit with her fellow cheerleaders. Kate briefly looks at Lizzie and acknowledges her debt to her, but just as quickly she and Claire shoot back a nasty look, letting Lizzie, Gordo and Miranda know that things are back to normal. And it looks like that's the way everyone wants it to be.
Meanwhile, Matt comes home with big news--he got a one-line part in a school play. With Lanny's help, he constantly practices his one line, but he gets the ego of a leading man. Soon he is ordering his mother around like she's his flunky, much to her irritation. His treatment of Lanny also drives him away. Mr. and Mrs. McGuire put their foot down on Matt's behavior, but when he starts to protest he loses his voice. A humbled Matt apologizes to his mother for the way he acted and he apologizes to Lanny too, who agrees to take over his part! (No, we don't see or hear Lanny at the play!)