Liv, Maddie and the rest of the Rooney family are excited to start their new life in California. As the school year begins, the Rooney's cousin, Ruby, returns home from a summer trip. Excited to have "sort of" siblings, Ruby can't wait to finally be a sister but finds herself in the middle of a sister-fight between Liv and Maddie. Meanwhile, Joey and Parker attend their new Science and technology school and their experience is not what they expected.
