Erin and Aaron's first day as step siblings and they are in no mood to get along. But when they discover that their differences may lead to a family break-up, they must find a way to come together.

Erin and Aaron clash over Saturday night traditions: Erin wants pizza and Aaron wants sushi; Chuck and Natasha have a special daddy-daughter day planned but struggle to find a shared activity they'll both enjoy.

When Erin and Aaron upload their songs online to choose which one to perform together at Asbury Park's "Porchfest", a Grammy-winning producer reaches out with a life-changing offer for one of them.