The Cimorelli siblings have a sister! Sophie seems perfectly nice to 12 out of the 13 Cimorelli family. Only Dani knows what Sophie really is, a big bully. When she tries to tell her family, no one believes her. They all think Sophie is a nice, kind, sweet, helpful girl who can do nothing wrong. Dani tries to ignore Sophie's hate, but soon she starts to believe that she's ugly, fat and can't sing. Will any of the Cimorelli family finally see what Sophie really is? or will Sophie bring Dani down?