Pack your overnight bag, because Junie B. Jones is heading to her very first sleepover! When Lucille invites her two best friends for a sleepover party, Junie B. and Grace cannot contain their excitement. They are not just going to any normal house, they are going to Lucille's rich nanna's giant mansion! Junie B. is absolutely certain that spending the night in such a fancy place will be a dream come true. She cannot wait to see all the expensive things and bounce on the giant beds. But as soon as the girls arrive, the fancy sleepover starts to spin hilariously out of control. From exploring rooms they are not supposed to enter to causing chaos in the grand hallways, Junie B. quickly proves that being a party animal in a very strict nanna's house is a recipe for total disaster.