Season 4 is set a few months after Dexter and Rita's wedding. Dexter and his family have moved to the suburbs and he struggles to reconcile his life as a family man and his killing urges. Dexter stumbles upon Special Agent Frank Lundy, recently retired from FBI. According to Lundy, the murder may be work of a serial "Trinity Killer", because he always kills three people in a sequence: First, a young woman is killed in a bathtub, then an older woman, mother of two falls to her death, and finally, a man also a father of two, is bludgeoned to death.