In the season three finale, Liv and Maddie get into a big disagreement while trying to figure out if they'll be together for the next four years or be going their separate ways.

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.

Liv takes Ruby to a spooky dinner and runs into an old acquaintance and Maddie comes face-to-face with the real-life spider-sprayer. Meanwhile, Parker and Joey must convince their classmates to celebrate Halloween.

Liv's new show is in danger of being canceled because they can't find the right cast; Liv helps by searching for the perfect star; Parker plans to take Joey and his new Falcon persona down by having Joey test-drive a dangerous invention.

Joey is nervous when he's invited to perform stand-up comedy at a local restaurant. Parker finds himself in a predicament.

After exciting opportunities arise for each of the Rooney children, their summer plans are thrown into jeopardy.