The season begins with Dexter and Rita settling into their new life. But when a mysterious arsonist starts terrorizing the city, Dexter's curiosity is piqued. He soon discovers that the arsonist is none other than a fellow forensic analyst, Arthur Mitchell (Colin Hanks).
Meanwhile, Debra continues her climb through the police department while struggling with personal turmoil and the lingering effects of previous seasons’ events. Side arcs include Masuka’s reassignment, Batista’s family issues, and Dexter’s attempts to maintain normalcy with his son and girlfriend. The climax ties Dexter’s personal crisis into the Doomsday Killer plot in intense, morally ambiguous ways—leading to outcomes that were praised by some viewers for boldness and criticized by others for plot choices. dexter season 6 link