What is sonny with a secret about in Sonny With a Chance?

When Sonny returns to her hometown high school for Homecoming, someone on set begins to spread rumors that Sonny is a thief, causing her reputation to deteriorate and she is ultimately asked to leave the show. Unable to clear her name, Sonny drives cross country to Wisconsin with Tawni, who turns out to be a surprisingly good friend. Meanwhile back in Hollywood, Chad, Nico, Grady and Zora discover the truth.