Gavin is Doug's millionaire brother who organizes a lavish birthday celebration for their dying father, Gordie. He experiences a tense rivalry with Doug and clashes with his own family regarding Gordie's wishes. After inadvertently exposing his wife Margaret's struggle with depression, he reconciles with Doug, breaks down emotionally at the shore, and co-hosts a beach memorial to honor Gordie while resolving their longstanding sibling feud.