After Isaac is about a young boy named Aaron Saturn, who lost his brother to a sudden and tragic heart attack. Aaron lives day by day, struggling to move on. Even with the support of the people around him, Aaron struggles in his life. Aaron learns that nothing can replace his brother Isaac, and many conflicts occur as his parents are trying to move on. To rebound from the constant thought of losing his baby brother, Aaron turns to rebellion and poor decision making. Soon after, Aaron meets Kim, a sweet girl from New York's Upper East Side.