"Lemonade Mouth" introduces an unlikely ensemble of five students - Olivia, Wen, Stella, Mohini and Charlie - who, after meeting in detention, gradually realize their shared musical connection and belief that it's time for the students of Mesa High to stand up and be heard on things big and small (ranging from the school principal's exclusive support of the athletic programs to the removal of the popular organic lemonade from the cafeteria).

Ultimately, as they open up to each other and form friendships, they start a band - Lemonade Mouth - that soon resonates with students sidelined by the high school elite. However, not everyone in the school is ready to cheer them on, especially since the popular rock group Mudslide Crush is determined to maintain their headline status and win the coveted Rising Star music competition at Mesa High.