Hal and Harper, two codependent siblings living in L.A., are doing their best to navigate long-term relationships, friendships, and situationships. When their Dad makes a big announcement, the two are forced to consider the current state of their lives and their complicated childhood. While exploring the trauma of their past and the dramatic changes of their present, Hal & Harper & Dad chart their family's evolution while discovering how their intense bond has shaped how they interact with those they love, for better or worse.